Adding default tests to all CLI tests via MetaClass.

* All CLI tests will inherit some default tests from the base class:
  * test_positive_create
  * test_positive_delete (TBD)
  * test_positive_update (TBD)
  * test_negative_create (TBD)
  * test_negative_delete (TBD)
  * test_negative_update (TBD)
Improve metaclass for cli tests

* Don't override methods if already defined on test class
* Add dynamic data to tests if defined in test class or use the default data
Added positive delete tests to metatest class.