SASS compilation variable conventions update, focusing on basic colors, baseline variable usage for padding and margins, ui-depth extends, along with other small fixes. The intent with this is to not have any user-facing impact, and instead move us closer toward having files that use our newer sass conventions.

OPEN-304

* removing unused font-family-centric Sass variables
* removing unused graphic images and Sass references
* clean up of style removal fallout

* moving font-size to use @include font-size() mixin
* re-organizing vendor reset styling into _vendor.scss override rather than _reset.scss
* initial rule re-organization and minor line-height tweaks

STUD-1186