add tests for security_group updating

make a seperate file test_security_groups_negative.py and move exist
negative tests over to it,also add some tests for security group updating.

Change-Id: I9ba5a1572e8f887e7b5f0222b399ee46658dbda1
Add basic read-only tests for heat cli

Adds some smoke-tests for the heat CLI interface, similar to what
exists for other projects - it's not an exhaustive test but it
provides coverage of the interfaces which do not require content
to be created or modified.

Change-Id: I9921815bfb17fbe4d010d41e2a79a8d9b292271d
blueprint: tempest-heat-integration
Merge "Add basic read-only tests for heat cli"
Merge "add tests for security_group updating"