Tweaking defaults
Remove changing color on `strong`
Abstract code properties to a %code placeholder
Add alert classes
Tweak $roundness & $widget-roundness

There represent the default border-radius values for background
elements and widgets, respectively.
Tweak local variables so they don't interfere with global ones
Update FontAwesome to 3.1.1

Still missing utility classes, but I think I don't want to use the
default FontAwesome ones as they're designed to fit with Bootstrap.