factor test_dialects() out of test_all_dialects()
factor test_dialects() out of test_all_dialects()

community-ssu/telepathy-gabble,jku/telepathy-gabble,Ziemin/telepathy-gabble,mlundblad/telepathy-gabble,Ziemin/telepathy-gabble,Ziemin/telepathy-gabble,Ziemin/telepathy-gabble,mlundblad/telepathy-gabble,jku/telepathy-gabble,mlundblad/telepathy-gabble,jku/telepathy-gabble,community-ssu/telepathy-gabble,community-ssu/telepathy-gabble,community-ssu/telepathy-gabble