Bug 1095006 — Touch the RoomToken when touching the participant.

https://bugzilla.mozilla.org/show_bug.cgi?id=1095006
Actually, sorry to be a bit late to the party here, I probably missed that in another PR, but `setRoomToken` isn't a good name here since the rooms already have a token, which is what we use to access them (and not the authentication token as it's the case here).

We should rename these `setRoomToken` and `isValidRoomToken` to something different to not mix the concepts here.