Add virtenv dir and contents to .gitignore
Add virtenv dir and contents to .gitignore

Allow developers to use 'virtenv' for virtual environments.

Change-Id: Ic5054a600918ebc3851c6c6883692a976277cf87

stackforge/monasca-api,stackforge/monasca-api,openstack/monasca-api,sapcc/monasca-api,openstack/monasca-api,stackforge/monasca-api,openstack/monasca-api,sapcc/monasca-api,stackforge/monasca-api,sapcc/monasca-api