Summary:
Sign in form improvements:
1) Added context menu with "Paste" and "Reset" items
2) Added "Reset" button
3) When form is empty, simple click to it automatically pastes token from clipboard
4) Automatically sign-in after token is pasted into empty form
Reviewed By: mweststrate
Differential Revision: D21994724
fbshipit-source-id: 8605c7f9b96777036b1b20b69370fba499185911
f88d707dbb