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