[Users] NEW FEATURE: cacheless usrloc

Hi everybody, USRLOC module can now operate in a DB mode : DB_ONLY. This is a cacheless mode - no memory cache is kept, all operation being directly done into DB. This mode allows DB sharing between multiple proxies without the need of additional replication mechanism. Drawbacks: - some performance penalties due intensive DB usage - location watcher disabled (cannot be bind to a record into mem) => PA cannot be used - statistics do not work since events cannot be properly been traced without a mem cache Still to be done: - the get_all_ucontacts function (used by nathelper/mediaproxy for NAT pinging) use raw_query in order to increase performance by filtering the loaded contacts from DB. For more info, see: http://openser.org/docs/modules/1.1.x/usrloc.html#AEN252 regards, bogdan