Sass structure for 2.0

Currently we import the global variables file and mixins within each component. This means we have duplication of comments in output and a bit of difficulty for modifying these things if they aren't defaulted.

What we should do instead is, remove global variables. Each variable should be fairly specific to the task at hand. Anything getting used in multiple places should be a mixin we reference. As far as that goes, we shouldn't include mixins directly in each component file.

That will let mixins get overridden easily if developers really wish to do that. Then on the variable front, we can trim down the number of them, if not remove most of them completely since they aren't that useful other than colors. Which those can probably become a mixin as well to grab the provided color scheme.

Any other thoughts on this for V2?