Add support for profile theme color

[jonathontoon]

Twitter profiles support custom tint colors, which are also available on the verifyCredentials endpoint of the Twitter API. Originally discussed here.

Expected Behavior

Whenever I sign in with my Twitter profile, everything which uses the default blue tint color should automatically update to use the user's theme color.

Current Behavior

Doesn't exist. 😢

Possible Solution

Add the custom theme color to the userCredentials object in Redux, and then overwrite the usage of the main blue tint color when it's available. The biggest issue that would need to be tackled though is that currently all of the SVG images used are a single blue color, would need to implement some way to tint them or to move over to using a webfont.