Make current user online in PHP 

To solve some issues and boost up performance it's needed to move the greet command to PHP.

- [ ] Remove greet, session id etc from client 
- [ ] generate sessionId in greet command
- [ ] execute greet command in `appcontroller::index` 
- [ ] add sessionid to initvars
- [ ] update client so Chat.och.sessionId = initvar['sessionid']