Fix the return of remove_interface for a successful remove

Currently returns null on success

Author: john-westcott-iv

orionsdk/solarwinds.py

@@ -674,6 +674,7 @@ def remove_interface(self, node_name, interface_name):
         if self.does_interface_exist(node_name, interface_name):
             self.logger.info("remove_interface_by_name - interface_uri query results: %s", interface_uri)
             self.swis.delete(interface_uri)
+            return True
         else:
             return False