Add pip to requirements list
Add pip to requirements list

A possible solution to the bug reported by Peter Martini where
other dependencies are causing pip to become broken.  In this case
we attempt to upgrade pip via the requirements file.

Change-Id: I4b1f4c4241e20e061f15c7834199cb1a6cf5111c
Closes-Bug: #1459947

openstack/bifrost,bcornec/bifrost,EntropyWorks/bifrost,openstack/bifrost,devananda/bifrost,EntropyWorks/bifrost,bcornec/bifrost,devananda/bifrost