Some minor refactoring and lint love for CLI.

* Handled some much needed pylint issues;
* Removed python "executor" line from headers;
* Moved some repeated class methods to base CLI class;
* Removed robottelo/cli/org.py as it is old and refers to Katello;
Merge pull request #188 from omaciel/cli_lint_love_and_refactor

Some minor refactoring and lint love for CLI.