* refactor mdns to reduce code complexity
* unit tests

# File version information:
# $Id: TODO 1230 2011-03-22 06:41:47Z corti $
# $Revision: 1230 $
# $HeadURL: https://svn.id.ethz.ch/nagios_plugins/check_rbl/TODO $
# $Date: 2011-03-22 07:41:47 +0100 (Tue, 22 Mar 2011) $
