Automate deletion of Infrastructure and cloud objects

Added test for deletion of infrastructure and cloud objects
These tests are far too complicated and there is too much repeated code. Selecting the first Quad should (a) not be done as state above, (b) would be so much neater if the "resource_pool" or "datastore" were given as fixtures. Yes some of these are not necessarily going to be easy to produce eg. resourcepool, but we cannot go and randomly delete things from the vmdb.