Use FQDN if possible.

I have the problem that some systems are logged with their hostname only and others with the FQDN in our Graylog2. We have a test and a live net, which can be distinguished by their subdomain and I need that to separate the logging.
I did some tests with the getCanonicalHostName method on different systems and it always gave the FQDN, so that is the right solution for us.
It would be nice if that could be integrated in the next release.