test-muc-properties: make clearer assertions
test-muc-properties: make clearer assertions

The formatting of these assertions was unhelpful, and using assertEquals
gives us nicer messages when the assertions do fail.

Ziemin/telepathy-gabble,Ziemin/telepathy-gabble,Ziemin/telepathy-gabble,mlundblad/telepathy-gabble,mlundblad/telepathy-gabble,Ziemin/telepathy-gabble,mlundblad/telepathy-gabble