Upd readme
Fixed https://github.com/Sammaye/MongoYii/issues/77
Fixed https://github.com/Sammaye/MongoYii/issues/78
Fixed: https://github.com/Sammaye/MongoYii/issues/79
Merge remote-tracking branch 'upstream/master'
Fix tests work w/o replSet
Merge remote-tracking branch 'upstream/master' into writeConcern
Merge branch 'writeConcern'
Fix MongoWriteConcernBehaviorTest work if run all tests