[Review] Request from 'vlewin' @ 'SUSE/connect/review_140617_should_raise_zyppererror_with_proper_message_if_call_returns_bad_exit_status_and_error_message_is_empty

Please review the following changes:
  * 6d4579b ZypperError with proper message if call returns bad exit status and error message is empty
  * a46c5f6 require irb/completion
  * d544376 Merge pull request #112 from SUSE/review_140616_revert_ca_certificates_suse_installation
  * f8f093d Merge pull request #111 from SUSE/review_140616_add_email_parameter
  * 1b411b2 revert ca-certificates-suse package installation
  * 5f15730 Silence Rubocop, class length is fine
  * 636ea5b Remove duplicate test, likely copy&paste mistake
  * 2d86a49 Add optional email CLI switch