Improve logging in message_route()
Revert hostname conflict detection

It is possible to use several frontend OpenERP servers, with only one
database, thus the conflit detection introduced in commits 9861b5c and
4ed8413 does not make sense in all cases.
Strip In-Reply-To header

Header could be expressed like this:

In-Reply-To:
	<4ba8f246904b4fedb49fbab7945a7f82@AM3PR06MB433.eurprd06.prod.outl$$k.com>

The message lookup fails if header is not stripped