removing whitespace from css files
adding basic/problem-centric styling support and FED fixes:

* adding in missing Font Awesome font assets
* correcting path for Open Sans typeface
* correcting typo in notes of openassessment IE-specific Sass
* syncing up variable names/values
* adding additional wrapper--grid element into layouts for easier grid-based styling
* syncing up variable names/values
* initial grid/view-based styles
* initial typographical styles
revising markup and styling for oa_*.html templates:

* matches static template expected markup
* adds in missing classes
* revises indentation/nesting
* adds in system__element markup/styling for system-based DOM elements
Adding a bunch of collapsed templates and javascript to load them.
Creating collapsed styles for each list item in the collapsed templates.
adding missing root class of 'wrapper--xblock'
removing static prompt collapse/expand UI control
syncing up basic markup/styling
adding 'block header' abstration to peer/self assessment step templates
syncing self assessment step markup with other step-based standards
cleaning up spacing within template markup
removes the 'is--unavailable' state from styling
styling general frame UI revisions, prompt, and response
adding in check icon to step status UI
differentiating between collapsed and general submitted response step view
styling submitted visual state and submitted response UI
creating longanswer UI Sass extend for submissions
reducing visual weight of step__counter border in step UI
increasing letter-spacing for any title-cased typographical treatments
revising visuals for displayed response UI