Tests to associate puppet repo/modules to cv

-added a method ` puppet_module_add` to add puppet module to cv
- Define `PuppetModule` class under robottelo/cli/puppetmodule.py to list the modules from selected repo
- Added following tests:
 - `test_cv_associate_puppet_repo_negative`
 - `test_cv_associate_composite_dupe_repos_negative`
 - `test_cv_associate_composite_dupe_modules_negative` -- blocked with bz `1089905`