Dark Theme - Or other theme?

[turnerniles]

Add dark theme or other theme. Get rid of funky theme?

Step 1: Add dark theme option object to the colorPack dropdown
https://github.com/turnerniles/react-virtualized-pivot/blob/master/src/app.jsx#L207-L208

Step 2: Add an additional if statement in the onColorPackSelect function. And change the colors to be in dark mode. The grid being maroon and black as current is not bad but it doesn't coordinate well with the menu colors.
https://github.com/turnerniles/react-virtualized-pivot/blob/master/src/app.jsx#L95-L119

[turnerniles]

@jaredwent May the best man win