This cleans up various bits of the avd support in Creator.
- Adds a abi combobox to the create avd dialog.
- Moves the startAvd code into a separate thread, so that
  starting a avd while deploying doesn't block creator anymore.
- Implements a better waitForAvd function that works even
  if a emulator is already running and accurately can
  detect that it has finished booting.

Note: There are still many problems in the avd support in creator.
- The "clean libs on device" and "install qasi" functionality block
  the gui thread if they are run on a avd.
- If no avd exists and no suitable hardware is attached, the user gets
  a create Avd dialog, which doesn't tell him why he needs to create a
  avd. That information is hidden in the compile output.

Still this fixes the main use case of hitting run on a newly created
project with no actual device attached.

Change-Id: I76b3fdb1bdf3eadac07f82ad7d145ce6af453326
Reviewed-by: BogDan Vatra <bogdan@kde.org>