Add pykmip

Add PyKMIP library, which is required to support KMIP as a secret
store within Barbican. Support for KMIP within Barbican has been
under active development -- see the "Support KMIP" blueprint at
  https://blueprints.launchpad.net/barbican/+spec/support-kmip
as well as the following change requests
  https://review.openstack.org/#/c/91107/
  https://review.openstack.org/#/c/101582/
  https://review.openstack.org/#/c/117539/
that implement this feature as an optional backend (i.e., "secret
store") for Barbican.

Change-Id: I315f9206dfc07fb2c4e342f6bd8b78c4079e6a5b
Merge "Add pykmip"