Create design system resources in UILibrary

[ryaanahmed]

@lukehollis is going to take the lead in creating some resources so that we have consistent design across the whole project, and so that our apps mesh nicely into the overall edX design. This is a tracking issue to discuss that work. A few things that came to me while working on #41:

• Match our type system with edX
• Grab some of the standard edX colors for use in our apps (they use a bunch of blues and teals all over the place that we can use as our standard 'primary' and 'secondary' interaction colors) and override Bootstrap defaults with these
• Setup a color system
• Create some standard button, slider, etc. components that can be used across our system