Create color utility classes

[ericwbailey]

Color utility classes will help us consolidate some layout styles by decoupling color from layout logic. For starters, we'll need to create:

• Text color classes
• Background color classes
• Fill color classes

Colors should utilize our color variables.

[danielmatthew]

@ericwbailey May I take this?

[ericwbailey]

@danielmatthew That'd be great, thank you!