Customizable UI Theme

[Darlington02]

Currently, buttons are themed orange as the primary colour, and blue as the secondary. Make this customizable in that from a single file, one can set the primary and secondary color for the buttons. e.g

Primary = "Red" Secondary = "white"

should make all the buttons across all pages, a mix of red and white. where red will replace the existing orange, and white replace existing blue.

PS: The default setting if not manually tampered with should be the existing orange and blue colors.