Add libvirtd logging test case.

This case check error messages in libvirtd logging.

Implemetent test cases:
* start_with_iptables:  Simply start libvirtd when using iptables service as firewall.
* start_with_firewalld: Simply start libvirtd when using firewalld service as firewall. This is a regression test for a known firewalld bug <https://bugzilla.redhat.com/show_bug.cgi?id=1070683>

Signed-off-by: Hao Liu <hliu@redhat.com>