- In the case of an invalid account import, lrc adds an account
  and removes it only after an erroneous state change. So we
  ignore accountAdded signals pertaining to accounts with empty
  usernames, and return the user to the wizard's welcome page upon
  receiving either the accountRemoved or invalidAccountDetected
  signals.
- This patch makes LRCInstance inherit from QObject so it can emit
  the accountOnBoarded signal when account creation has succeeded.

Change-Id: I43e4ba168fac96d4bd86171639ae8d4776d5cada