extracted DNSUtils from filter and cleaned up some dependencies
renamed dnsutils to utils and fixed filtertestcase
added support for matching IPv6 addresses in loglines
adjusted <HOST> regexp to match all test cases
added some v6 test cases
moved DNSUtils methods to submodule level
Merge branch 'pr_469'

Conflicts:
	fail2ban/server/filter.py
	fail2ban/tests/files/logs/sshd
	fail2ban/tests/filtertestcase.py