Update cache when creating or updating MUCs

[Fishbowler]

When clustering, the MUC goes into the cache, but doesn't get an ID, and the savedToDB value is incorrect. No idea if this has any real world impact, but it's certainly wrong. This forces a sync the same way that Admin does when it creates a room.

Could this be #30?

[guusdk]

I'm not yet sure if I understand your underlying issue, but synchronizing the implementation to what Openfire itself is doing, makes sense. Ideally, we introduce some easy-to-use API in Openfire that can be used for this purpose, instead of copy/pasting boilerplate code.

[Fishbowler]

Have added to #30 (comment):

When I'm in a cluster and I create a room, the room exists properly in the database, but is incorrect in the cache. When I look at it in the cache, the settings are wrong, the ID is -1, and the savedToDB value is False.

I've not played with the effects of this, but suspect that if the cache is incorrect, it'd lead to all sorts of problems until the server is next restarted or the cache is otherwise repopulated.