Merge #2088: Update Zenmap to Python 3 and PyGObject

Note: Ndiff build will be broken until subsequent changes are made.
Deprecation warnings will need to be addressed in future changes.
Closes #2088

zenmap/test/run_tests.py

@@ -1,4 +1,4 @@
-#!/usr/bin/env python
+#!/usr/bin/env python3
 
 import unittest