Controller rework.

- Controller.Result is now a class rather than an interface,
  so subclasses don't have to implement empty methods.

- Replaced Threads with AsyncTasks, which is more light weighted
  because it uses pooled threads.

- Removed the Result argument from Controller's methods.
  These argumetns weren't used, except in serviceCheckMail.

  Regarding serviceCheckMail, the new code behave differenly from the old code.
  If there's already listeners registered when it's colled, they wouldn't get
  called in the old code, but they will in the new code.
  But I think this difference is okay because that's how it works for
  POP/IMAP accounts.

Change-Id: I37a857ce7c089c1a411cb7f1fcfcb72c9f5fd2a6
9 files changed