Ensure that plumgrid pip install takes extra args
Ensure that plumgrid pip install takes extra args

In https://review.openstack.org/231214 the inclusion of the pip
install extra arguments was missed. This patch remedies that.

Change-Id: If40e03197cec9f31c111f150243ef4cf5f70fc40

michaelgugino/openstack-ansible-os_neutron,michaelgugino/openstack-ansible-os_neutron