test_auth_and_roles works with the new nav menu structure

* Also tweaked the menu locators a little bit so hopefully they're easier to use
auth and roles tests use testgen and are parametrized from cfme_data

- Due to the way pytest.skip works in collection (see note in utils.testgen),
  it made sense to break these up into separate modules so testgen could do
  its job easily.
- I *think* the old configure_auth_mode in fixtures has been completely replaced
  by cfme.fixtures.configure_auth_mode...
I'm not sure where reverse_lookup and visible_pages belong...

..but I'm sure that they belong together wherever that may be
Merge pull request #602 from seandst/nav-auth-fixup

Nav auth fixup