Use APIUser for _hostgroups2json, _servicegroups2json and _hostgroup2json
Test comment update
Remove SQLite code from Session.__init__
Remove sqlread()
Add host fiter to Session.buffer2json()
Remove SQLite code from Session.reg2key()
Remove SQLite code from Session.state2state()
Remove SQLite code from Session.state2buffer()
Remove SQLite code from Session.buffer2json()
Remove Session.init_userdata() - APIUser takes care
Merge branch 'sqlite-removal' into devel
Import sqlite3 only to ServiceData and ControllerData
Code cleanup