fix(client): The Sync flow should not notify the browser of login after the signup confirmation poll completes.

The browser polls in the background for the status of the sign up completion itself, the client does not need to notify it of completion.

In addition, the /confirm screen should not transition to the /signup_complete screen, this causes a jerky UI.

fixes #1881
fix(client): Notify Sync of unverified logins and signups before the user verifies her email (regression fix)
Fix the jshint error, add unit tests for beforeSignUpConfirmationPoll
Fix the failing 'choose option to customize sync' functional test.

The test was failing because it was not listening for FxA commands and the channel was timing out when sending the `login` message in FxDesktopBroker's `beforeSignUpConfirmationPoll`

Test is moved to sync_sign_up.js where the rest of the Sync tests live.
Merge pull request #1887 from mozilla/issue-1881-sync-no-confirm-redirect

fix(client): The Sync flow should not notify the browser of login after the signup confirmation poll completes.