websocket: Improve connection registration

Change-Id: I9042504bceaa42185cb47e691d4f413d0b23ef5c
websocket: Perform keep alive of active connections sessions

Change-Id: I575798325cdfaf8f67106e8200a434577c8eef15
ServerMethods: Use constant for sessionId key

Change-Id: Idb78a4a5123a0bc40466efe9afc5ae1c6d8adb0a
websocket: Inject session id on requests

 If current connection is associated with a sessionId and incomming request
does not contain a sessionId

Change-Id: I968bfd8ee36a16a5d40a44adb3053d4874507e6b