Configure swift credentials for workers to push to

This change adds credentials as set up by fungi (2014-04-05T03:16:46)
http://eavesdrop.openstack.org/irclogs/%23openstack-infra/%23openstack-infra.2014-04-05.log

This allows zuul to send signed URL's for workers to push files to on
a per-job basis.

This change will require a zuul restart, not just a reload!

Note this is unreverts the revert in
c1b98eaff618b8c739cc02f089ef6fe6c02cbcc3 but is slightly edited hence
the lack of a proper revert commit. The reason for the revert has been
debugged and was due to rax identity service not providing a catalog
entry for swift when a tenant name is provided.

Change-Id: I04d3207002f7422b9851515ee88a74b19dd2f248
Merge "Configure swift credentials for workers to push to"