Add tempest test for CFN API

[Zhang Yang]

In order to be compatible with Cloudformation, we have CFN API in heat, but
there is no API tests in Tempest, we need to add the missed tests to verify
changes and make heat stable.

    - test stacks (create/update/delete/list/describe)
    - test resources (list/describe) 3
    - test events (list)
    - test template (get/validate/estimate)

[Steve Baker (steve-stevebaker)]

Since this is a compatibility API, it should live in tempest/thirdparty. Also since boto supports the CloudFormation API, and attempt should be made to use boto to write these tests.

However be warned that we've traditionally had issues with different versions of boto and generating requests with auth signatures which heat recognises as valid (just something to keep in mind).

[Zhang Yang (neil-zhangyang)]

stevebaker,
   yes, as you said, we should integrate boto.cloudformation in boto test first, I will study it and then think how to do this job properly.