A change is coming to Ansible where module params will default to str.
Many of our modules were taking advantage of this by not being explicit
about the type, so they will break when that change merges. This hopefully
catches those cases.
The exception message, when shade fails, will contain much more
specific information about the failure if the exception is treated
as a string. The 'message' attribute alone is usually not helpful.
There can be instances during an Ansible play where the list of subnets
currently available from OpenStack is required. This update provides
subnet list functionality as a new os_subnets_facts module.
