Add accent color

Accent color is the A200 level of Deep Purple, from
http://www.google.com/design/spec/style/color.html#color-ui-color-palette
Initial FloatingActionButton (commented out)

Implementation taken from
https://gist.github.com/Jogan/9def6110edf3247825c9

Commented out until I get used to the idea, and until I get it fully
implemented.