Fix thread termination issues connected with timer module

* Cancel timer after sending TimeoutMessage
* Remove double injection of RandomPeersGossipingModule

Change-Id: I9fe75175be53f9498362e8c4fdc15492c7d074ec
Reviewed-on: http://naan.mimuw.edu.pl:8001/123
Tested-by: Nebulostore Nebulostore <nebulostore@gmail.com>
Reviewed-by: Grzegorz Milka <grzegorzmilka@gmail.com>