[Review] Request from 'aduffeck' @ 'SUSE/pennyworth/review_140731_add_missing_exception_class'

Please review the following changes:
  * ada3481 Add missing exception class
  * f4b0967 Merge pull request #1 from SUSE/add_prophet_to_pennyworth
  * b251b93 Stub Vagrant directory initialization test
  * 0b9cc28 Add requirements to run Prophet