Fix issue where sending 'stop' pendingintent would resend 'start'.

This was due to the pending intent being updated in two places, so the
start intent was overwriting the stop intent's extras. Have switched to
intents with non-matching actions to avoid filterIntent() related bugs
in the future.
Add snapshots repo.
Prepare for release.
Fix issue with service not shutting down when started and unable to sync.

Also mitigates issue caused by system starting service with null intent.
Don't understand why this is happening (not mentioned in
START_NOT_STICKY docs), but fix is the same.
Compatibility fixes for upstream change.
Fix sync button status not updating when login details added.

This was introduced by the switch to viewpager navigation; can no longer
rely on onResume() being called when returning to fragment.
Show proper error messages by unwrapping exceptions in notif manager.
Remove some unnecessary logging.
Integrate ACRA (crash reporting).