Changes include:
* New markup for the button in compose.html
* A hidden file input field in compose.html
* Added reference to the file input field in filedrop
initialization in compose.js
* A feature test and a click event binding for
the "Attach files" button in ui.js
* New paperclip icon reference in fonts.css
* New general hidden display classes in zephyr.css
* New composition pane button classes in zephyr.css
Fixes to the "Attach files" button commit e673bda...
Changes include:
* Fixed the feature test for (new XMLHttpRequest).upload so
it works in Firefox.
* Renamed .button to .message-control-button
* Removed stray newlines
(imported from commit c1f0834b74fd7120ec27db64ec380ffb3fa34633)
* renamed the 'icon-star' style to 'icon-vector-star' to keep backwards compatibility for icon-* classes
* changed relevant styles in zephyr.css; added FontAwesome assets
* changed relevant CSS classes in base.html, left-sidebar.html, ui.js, message.handlebars
* added new fonts.css to start consolidating all font-based assets
* added fonts.css to PIPELINE_CSS in settings.py under 'portico' and 'app'
* modified the stars test suite to reflect new star icon class name.
(imported from commit 3116fcfd4b5fb4edecd457da554fea616bb7081b)