fix for Ubuntu six pip package, added to the crowbar.yml for
downloading the latest version via pip

Version upgrade is required, because for current
neutron-server required the six version above 1.4.2
metering_agent service name is fixed for Ubuntu.
Missing cache directory creation is added for Ubuntu.
Missing ml2 plugin directory creation is created for Ubuntu
Missing package name is added for Ubuntu installation process.
neutron-server run fix for Ubuntu.

while running neutron-server, ml2 plugin is not added as config file
to the paramater list.