Merge branch 'master' into v4

Conflicts:
	.travis.yml
	Gruntfile.js
	bower.json
	dist/css/bootstrap.css
	dist/css/bootstrap.css.map
	dist/css/bootstrap.min.css
	dist/js/bootstrap.js
	dist/js/bootstrap.min.js
	docs/_data/glyphicons.yml
	docs/_includes/components/breadcrumbs.html
	docs/_includes/components/button-dropdowns.html
	docs/_includes/components/button-groups.html
	docs/_includes/components/dropdowns.html
	docs/_includes/components/glyphicons.html
	docs/_includes/components/labels.html
	docs/_includes/components/list-group.html
	docs/_includes/components/media.html
	docs/_includes/components/navs.html
	docs/_includes/components/panels.html
	docs/_includes/components/progress-bars.html
	docs/_includes/components/thumbnails.html
	docs/_includes/components/wells.html
	docs/_includes/css/buttons.html
	docs/_includes/css/forms.html
	docs/_includes/css/helpers.html
	docs/_includes/css/images.html
	docs/_includes/css/less.html
	docs/_includes/customizer-variables.html
	docs/_includes/getting-started/accessibility.html
	docs/_includes/getting-started/browser-device-support.html
	docs/_includes/getting-started/community.html
	docs/_includes/getting-started/examples.html
	docs/_includes/getting-started/grunt.html
	docs/_includes/getting-started/license.html
	docs/_includes/getting-started/template.html
	docs/_includes/header.html
	docs/_includes/js/affix.html
	docs/_includes/js/alerts.html
	docs/_includes/js/carousel.html
	docs/_includes/js/collapse.html
	docs/_includes/js/dropdowns.html
	docs/_includes/js/modal.html
	docs/_includes/js/overview.html
	docs/_includes/js/popovers.html
	docs/_includes/js/scrollspy.html
	docs/_includes/js/tabs.html
	docs/_includes/js/tooltips.html
	docs/_includes/js/transitions.html
	docs/_includes/nav/javascript.html
	docs/_layouts/default.html
	docs/assets/css/docs.min.css
	docs/assets/css/src/docs.css
	docs/assets/js/customize.min.js
	docs/assets/js/docs.min.js
	docs/assets/js/raw-files.min.js
	docs/assets/js/vendor/FileSaver.js
	docs/assets/js/vendor/autoprefixer.js
	docs/assets/js/vendor/uglify.min.js
	docs/dist/css/bootstrap.css
	docs/dist/css/bootstrap.css.map
	docs/dist/css/bootstrap.min.css
	docs/dist/js/bootstrap.min.js
	docs/examples/blog/index.html
	docs/examples/carousel/index.html
	docs/examples/cover/index.html
	docs/examples/dashboard/index.html
	docs/examples/narrow-jumbotron/narrow-jumbotron.css
	docs/examples/navbar-fixed-top/index.html
	docs/examples/navbar-static-top/index.html
	docs/examples/non-responsive/index.html
	docs/examples/non-responsive/non-responsive.css
	docs/examples/theme/index.html
	grunt/configBridge.json
	js/affix.js
	js/carousel.js
	js/collapse.js
	js/dropdown.js
	js/modal.js
	js/popover.js
	js/scrollspy.js
	js/tab.js
	js/tests/unit/affix.js
	js/tests/unit/button.js
	js/tests/unit/carousel.js
	js/tests/unit/modal.js
	js/tests/unit/tooltip.js
	js/tooltip.js
	less/badges.less
	less/glyphicons.less
	less/type.less
	less/variables.less
	package.json
	scss/_dropdown.scss
	scss/_forms.scss
	test-infra/npm-shrinkwrap.json

2 files changed, 12 insertions, 2 deletions

diff --git a/docs/content/forms.md b/docs/content/forms.md
index f1068a01b..ac056a8b9 100644
--- a/docs/content/forms.md
+++ b/docs/content/forms.md
@@ -336,7 +336,7 @@ We remove the default `outline` styles on some form controls and apply a `box-sh
 
 ## Disabled states
 
-Add the `disabled` boolean attribute on an `<input>`, `<select>`, or `<textarea>` to prevent user input and trigger a slightly different look.
+Add the `disabled` boolean attribute on an input to prevent user interactions. Disabled inputs appear lighter and add a `not-allowed` cursor.
 
 {% highlight html %}
 <input class="form-control" id="disabledInput" type="text" placeholder="Disabled input here..." disabled>
@@ -379,7 +379,7 @@ Add the `disabled` attribute to a `<fieldset>` to disable all the controls withi
 
 ## Readonly inputs
 
-Add the `readonly` boolean attribute on an input to prevent user input and style the input as disabled.
+Add the `readonly` boolean attribute on an input to prevent modification of the input's value. Read-only inputs appear lighter (just like disabled inputs), but retain the standard cursor.<
 
 {% example html %}
 <input class="form-control" type="text" placeholder="Readonly input here…" readonly>
@@ -389,6 +389,12 @@ Add the `readonly` boolean attribute on an input to prevent user input and style
 
 Bootstrap includes validation styles for error, warning, and success states on form controls. To use, add `.has-warning`, `.has-error`, or `.has-success` to the parent element. Any `.control-label`, `.form-control`, and `.help-block` within that element will receive the validation styles.
 
+<div class="bs-callout bs-callout-warning" id="callout-form-validation-state-accessibility">
+  <h4>Conveying validation state to assistive technologies and colorblind users</h4>
+  <p>Using these validation styles to denote the state of a form control only provides a visual, color-based indication, which will not be conveyed to users of assistive technologies - such as screen readers - or to colorblind users.</p>
+  <p>Ensure that an alternative indication of state is also provided. For instance, you can include a hint about state in the form control's <code>&lt;label&gt;</code> text itself (as is the case in the following code example), include a <a href="../components/#glyphicons">Glyphicon</a> (with appropriate alternative text using the <code>.sr-only</code> class - see the <a href="../components/#glyphicons-examples">Glyphicon examples</a>), or by providing an additional <a href="#forms-help-text">help text</a> block. Specifically for assistive technologies, invalid form controls can also be assigned an <code>aria-invalid="true"</code> attribute.</p>
+</div>
+
 {% example html %}
 <div class="form-group has-success">
   <label class="control-label" for="inputSuccess1">Input with success</label>
diff --git a/docs/content/images.md b/docs/content/images.md
index da5c6bf99..6b691fb0e 100644
--- a/docs/content/images.md
+++ b/docs/content/images.md
@@ -37,3 +37,7 @@ Add classes to an `<img>` element to easily style images in any project.
 <img src="..." alt="..." class="img-circle">
 <img src="..." alt="..." class="img-thumbnail">
 {% endhighlight %}
+
+## Aligning images
+
+To center images with `.img-responsive`, use `.center-block`. For all other images, use `.text-center`. [See the helper classes section](/css/helpers) for more details about `.center-block` usage.