Restructure modules to reduce import-time side effects

Summary:
`flipper` does a lot of stuff at import time. I copied the `styled` reexport
to the UI module, so it's possible to just depend on that.

`remote` is another one of those pot holes that can easily ruin your journey
if you aren't careful navigating around it. Added some defensive fallbacks here
which ultimately allows the lint test to run (and pass) without Electron.

Reviewed By: danielbuechele

Differential Revision: D10507655

fbshipit-source-id: 6dad5665ba15b5cb73caa4ea46262cf337173eb8

src/ui/index.js

@@ -5,6 +5,7 @@
  * @format
  */
 
+export {default as styled} from 'react-emotion';
 export {default as Button} from './components/Button.js';
 export {default as ToggleButton} from './components/ToggleSwitch.js';
 export {