Summary:
* Removed Flow compilation step
* Removed all `flow` annotations
* Removed all FlowFixMe's
* Removed flow typings for Flipper
* Left flow transpilation (stripping) in babel, in case there is any external user using Flow in his plugin
* Left `eslint-plugin-flowtype` dependencies, as `eslint-config-fbjs` requires it
Reviewed By: passy
Differential Revision: D24755545
fbshipit-source-id: 9c0a7910657fd1cba88294e041bf2bfdf7b565bf
670be012b2