Updated openstack/openstack
Project: openstack/python-keystoneclient  f252161bb3c2c48cbe9e9a61cb2ebf726f800e60
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Make HACKING.rst DRYer and turn into rst file

Rename HACKING to HACKING.rst since it is a rst file and
reference the OpenStack hacking guide and remove
duplicated entries.

Change-Id: I9994594c7f8cb0f011d949b273bea08c68985e16