Stratum: Renamed addons to helpers
Stratum: Font icons helper
Demo: Initial icons demo page + Font Awesome icons
Demo: BBC - remove row element
Demo: Mock block to use CSS3 mixins
Stratum: Reorg, optimisations and bug fixes

Includes:
* Lots of refactoring & housekeeping
* Various grid bug fixes
Demo: Various test cases updates
Demo: Moved from Jekyll to Middleman
Demo: AngularJS - interactive test cases
Stratum: Helper - Border triangles
Updated local variable notation ($-variable)
reorganising gem lib/

Conflicts:
	.gitignore
Fixed stylesheets path