Bugfix. Updates #32

Users without roster contacts didn't have XMPPStatus.initStatus called and
therefore had a default status of offline.

Fixed this by setting the status to online from the start. The fetch command
will get the true status from localStorage (if available).

Made sure that the rest of converse's onConnected code is called in the
callback from fetch (so that we know the user's status is correct).

Updated and fixed tests.