All client interactions should actually flow through a keystoneauth
Session. Add the parameter for a user to pass one in, but support
the old style of direct parameters too. A followup patch will add
os-client-config support to the shell, so add that to requirements.txt
instead of keystoneauth directly to look forward.
Also, trim unneeded things from requirements.txt because we're adding
os-client-config which pulls in various things.
Closes-Bug: #1514733
Change-Id: I88b1d0e4e119429599dec75c5db24237a92edcec
5cbc5e722e