Distributions provide packages for the OpenStack services so we add
support for using these instead of the pip ones.
Change-Id: I7eb1cbe2c80ee889d2ae08dcfed6a19cc1bd3415
Depends-On: Ide70b5d8f67d8c8a87e3f16671f0f7fb72338b89
Depends-On: I8de48eb1fb4c8d321098ca54b9e21270edc7ac87
Depends-On: Ia5fda5d417b79189d048c8891b84d57331df1404
Implements: blueprint openstack-distribution-packages