User tests and the constants they require
Merge branch 'master' of https://github.com/omaciel/robottelo into user-test-merge

Conflicts:
	robottelo/ui/user.py
flake8 cleanup
Merge branch 'master' of https://github.com/omaciel/robottelo into merge-user-tests
ddt test fixes and some pep cleanup
removing __init__() from users.py
removing test_negative_create_user_7 stub
making pep8 happy
Adding assertions and make_org factory,
removing redundant string generation
Merge branch 'master' of https://github.com/omaciel/robottelo into merge-user-tests
Merge pull request #649 from blrm/merge-user-tests

UI User tests
Refactor cli to better handle organization-id

* Unify the expected parameters for cli methods
* Give more flexibility to exists method