Client for Moztrap API

That's just an example of how client for Moztrap API might look like. 

Actually it's working for those 4 methods that are implemented and I changed `test_for_edit_active_run_that_includes_suites_to_be_sure_they_are_listed` test to use Moztrap API within it. That chage allowed to reduce test execution time for 110 seconds.

I have no intention to merge this pull request right now, but it would be great if anyone can review the code and say is this good or not.