Bug 956844 - Part 4: WIP towards better state machine.

Bug LOGIN - Allow {session,keyFetch}Token to be null.

Bug LOGIN - Start refactoring states.

Bug LOGIN - Refactor FxAccountLoginPolicy.

Bug LOGIN - Present quickStretchedPW to createAccount and login{AndGetKeys}.

Bug LOGIN - Let FxAccount instances be permanently invalid.

Bug LOGIN - Moar state machine, moar tests.

Bug LOGIN - Ease debugging.

Bug LOGIN - Fixes for QA.
Bug 951304 - First cut at native UI.

Bug UI - Add password length restriction.

Bug UI - Enable and disable create account and sign in buttons.

Bug UI - Make input fields blur when disabled.

Bug UI - Style and implement show/hide password button.

Bug UI - Make status activity look decent.
Bug UI - First version of FxAccountUpdateCredentialsActivity.
Bug 956844 - Part 4: WIP towards better state machine. r=rnewman
Bug 951304 - First cut at native Firefox Account UI. r=rnewman
Bug 951304 - First version of FxAccountUpdateCredentialsActivity. r=rnewman