Automate deletion of Infrastructure and cloud objects

Added test for deletion of infrastructure and cloud objects
The issue isn't with `get_vms`, it's that the behavior of getting all the quads is generically useful, and for it to be buried in a method not directly related to quadicons (from the usage perpective) means that it's likely to be reimplemented elsewhere and cause code fragmentation. I second @mfalesni's `@classmethod` suggestion.