Introduce StumblerService.

The StumblerService runs in the application's process and
does not contain the notification / low battery bits.
Remove mLooper from the service.

It looks like the only reason why it was being used was so that
date synchronization could happen in a separate thread. Ever since
we started using a sync adapter, this is no longer a concern.
wip Split reporter in two.

The current Reporter is responsible for syncing the scanner streams,
and actually formatting and uploading data. The first task will in
the future yield a StumblerBundle, which is broadcast by the library,
so that the application can take care of the second task.