Revise how project variables are handled by styleguide

[beckkramer]

Currently, two areas come into play where Sass variables need to be accessed by the styleguide directly: Color Swatches and Breakpoints. Both areas currently require the project's Sass file be imported in with the styleguide's Sass files to function as expected.

Given that both breakpoints and color swatches are rendered in/augmented be the styleguide with JS anyway, it makes sense to handle these variables strictly with JS from the get-go. This will also make the build on the whole be less delicate/setup-dependent, which is a plus.

AC:

• A variable import solution has been found, vetted, and documented within the context of the styleguide
• Imported variables are folded into color swatch creation
• Imported variables are folded into breakpoint display