Enable gate jobs for Swift Cookbook

Enable lint and unit test jobs for object storage
cookbook. Initial patches for the cookbook expected
later today.

Change-Id: Ia4ecf5ad7097058844d2b2d4fc7d960a21fc4422
Reviewed-on: https://review.openstack.org/31504
Reviewed-by: James E. Blair <corvus@inaugust.com>
Reviewed-by: matthew wagoner <zxkuqyb@gmail.com>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins