Only take screenshot of failures if running local.

Remote tests are run on SauceLabs, which automatically handles screenshots.
You can now specify the Katello username/password.

* You can now specify the default username and password for your Katello
or SAM server. The defaults are admin/admin.
* Cleaned up code according to PEP8 warnings.
Adding decorator to skip tests.

Tests can be skipped based on the 'mode' that the server is running.
fixed user menu locators
Merge pull request #23 from sthirugn/usermenu

fixed user menu locators