Don't spawn thread to wait for SendWorker on handleSilentException()

Small optmization, but there's no reason to spawn a thread to wait
around on the SendWorker when invoked via handleSilentException(),
since there's otherwise nothing for that thread to do.
Small cleanup for PR#202 Don't spawn thread to wait for SendWorker on handleSilentException().
Renamed forceSilentReport param for better comprehension.
Merge branch 'master' of github.com:ACRA/acra