Added basic in-memory REST transaction storage. Only the latest transaction for a given path/access_token combo is stored in order to prevent storing ALL request/response pairs.

URL renaming: Room state keys now use the format /rooms/$roomid/state/$event_type/$state_key. cmdclient: Fixed double urlencoding on leave command. Stream from the END since START now produces an error on /events.

Adjusted webclient to use new state paths. Updated membership msg template to actually show the person invited. Factored out common membership functions in matrix service.

For the content repo, don't just use homeserver.hostname as that might not include the port due to SRV.