Add support for both Integer and String in VM#ipv4_address
Add a parameter `port_name` when adding interface
Merge pull request #13 from axsh/fix-for-compat

Add a parameter `port_name` when adding interface
Merge remote-tracking branch 'origin/master' into feature-datapath-event

Conflicts:
	lib/vnspec/spec/event_spec.rb
Remove :focus