On logout happens sometimes that `PeersCount` is called when the server
has been removed.
This commit adds a guard to make sure that the server is not nil when
calling `PeersCount`.
Currently messenger has no notion of being online.
This might cause a problem as we retry to register with a push
notification server even if not connected to any peer, which will
inevitably fail.
This commit adds a method `handleConnectionChange` that will be called
every time the connection change state.
Andrea Maria Piana
Pedro Pombeiro
Pedro Pombeiro
Adam Babik