Better placeholder behavior for multi-select

* Separates API into placeholder/persistentPlaceholder distinction
* Placeholder now defaults to undefined
* Better placeholder and query sizing
  * Uses an invisible span to determine the best width for the placeholder
* Tweak some CSS to improve the look of the multi-select

Piggyback:

* Remove spurious test code on select page
Release 0.2.0
Clean up demo app and migrate to gh-pages

* Restore Addepar app styles (fixes font and coloring problems)
* Fix usebanner in Gruntfile (no more disappearing headers)
* External links now link to other repos' gh-pages
* Use grunt-release-it instead of release-it
* Update README to point to new docs and describe new release process
* Allow for large hero on overview page
* Separate navigation/footer into their own partial views
* Move some dependencies and clean up build process a bit
Wrap bodyClick in Ember.run
Add the ability to toggle popover-link-component by clicking multiple times
Don't close select dropdown after it is destroyed
Add a `Ember.Widgets.DISABLE_ANIMATIONS` flag to be used for testing

Fixes #132
Fix animation on modal and carousel
Fix test dependencies
Fix ColorPicker unit tests
Fix findInMultiChosen to open the dropdown
Fix Text editor component functional tests
More tests passing

Arrow behavior between pills in Text editor with non editable pill
component functional tests is a real bug of the library.
Comment out TextEditor tests