Version bump to 0.7.0.
Added Service#extra_info.
Added Service#os_type.
Added Service#device_type.
Added Service#ssl?
Added Service#protocol.
Added Nmap::Hostname.

* Host#each_hostname now yields Hostname objects.
Added Traceroute, Hop and Host#traceroute.
Word on auto-generating the test XML file.
Connect spec task to scan.xml.
Clean all XML files.