Fix for https://www.pivotaltracker.com/s/projects/166935/stories/48602149

Cloud controller should return better error message when user tries to delete non-empty Space, Organization or any other objects which have dependencies. Current error message on this clunky and ungrammatical. Related to the 48602149 in Pivotal tracker
https://www.pivotaltracker.com/s/projects/166935/stories/48602149

Also related PR from cloud contoller module 
https://github.com/cloudfoundry/cloud_controller_ng/pull/102

Related PR from yeti tests
cloudfoundry/vcap-yeti#15