Removed possibility to run job w/o Oozie

* Added a validation function which checks if cluster contains oozie
  service in its node groups
* Added unit-test covers both valid and invalid cases when cluster
  contains and doesn't oozie service in attempt of job execution
* Fixed small issue in unit tests in validation utils where pathced
  api.get_cluster function had never been unpatched.

Change-Id: I5c5de6cfb1812ff6795797df63b8ec0292395fd1
Closes-Bug: #1291649
Merge "Removed possibility to run job w/o Oozie"