Use released novaclient in gating
Use released novaclient in gating

Since python-novaclient with microversion support (2.27.0) is released,
ec2api does not have to install it from git.

Change-Id: I1d17e5340128243597bd511cd4eb5006aedcfb5b

openstack/ec2-api,hayderimran7/ec2-api,hayderimran7/ec2-api,openstack/ec2-api,stackforge/ec2-api,stackforge/ec2-api