Remove stubbs and set up import rules

junipero.scss imports the framework from lib, views, and themes which
themeselfs are aliases to their respective areas.
Replacing import order for theme and libs

Since theme files contain all the variables for the framework
extensions they should be the first items imported.
Adding disabled extension

A disabled mixin that controls clickability, cursor, and opacity.
Defaults to no click, default cursor, and 0.5 opacity
Adding overflow mixin

A mixin that includes overflow aliases for ellipsed text, vertical &
horizontal scrolling:
@include ellipsis;
@include vertical-scroll;
@include horizontal-scroll;