[META] Remove deprecated items by 2.0.0

[cchaos]

Starting a list of deprecated items to remove by 2.0.0 release:

SASS

• Old responsive vars and mixins (Responsive refactors and addition of helpers #909)
• Old form control vars (Simplifying form control styles #954)

[snide]

Closable. I removed the responsive vars. Think you replaced the form stuff.