CFY-924: multiple security groups bug while installing

	neutron_plugin.security_group.create() will use existing
	security group if it has the same name, description and
	rules as requested.
CFY-924: multiple security groups bug while installing -- fix after review
Merge pull request #13 from Fewbytes/feature/CFY-924-use-existing-sg

CFY-924: multiple security groups bug while installing