Check for dead tunnels evry 5 seconds instead of waiting for the next tunnel_refresh

Conflicts:
	TODO

I've akso changed the datastructure to bz able to see the graph evolve much faster

Added exception catching in db, and modified utils.log so tht it can be used with anything ( and not only a string )

Conflicts:
	TODO
	tunnel.py

openvpns and babeld should now exit correctly