swiftclient, quantumclient, and cinderclient, are not optional

[Clint Byrum]

I see no reason to make these basic client libraries optional. They are listed in pip-requires and are equally available on any platform that has the others which are not conditionally imported. What should define whether or not swift, quantum, or cinder are available, is the keystone catalog and/or heat's configuration. I believe making them non-optional would remove all conditional import code.

[Steven Hardy (shardy)]

We've been trying to maintain some backwards compatibility, as we have existing users, some of which will still be using Folsom

Since we don't currently have a stable/Folsom branch, I think we need to discuss this and probably have a vote regarding the advantages and disadvantages of diverging. My feeling right now is that a few conditional imports are less-bad than the burden of doing lots of stable-branch backports.

[Matt Riedemann (mriedem)]

Isn't this invalid now that requirements.txt for heat on the master branch requires all 3?

https://github.com/openstack/heat/blob/master/requirements.txt

However, python-quantumclient should be changed to python-neutronclient.

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/37714

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/92498
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=05b0ff1155004ed4bbf80213ad5bfd33d3457643
Submitter: Jenkins
Branch: master

commit 05b0ff1155004ed4bbf80213ad5bfd33d3457643
Author: Angus Salkeld <email address hidden>
Date: Fri May 30 09:39:56 2014 +1000

    Remove optional imports from clients.py

    Why:
    - These are in the requirements
    - Heat is now well down the path of been a part of the integrated release
    - All of the above clients are also integrated.
    - If someone wants to use heat on an old OpenStack they still can
      as long as they install the required recent client libraries,
      which are backwards compatible with older OpenStack releases.

    Change-Id: I39d7dcbd3e5655d3da1c97de5ff7eceb1826d4ea
    Fixes-bug: #1174005