cloudstack: update code to match best practice

* Remove catchall exception
* use `if __name__ == '__main__':`

lib/ansible/modules/extras/cloud/cloudstack/cs_network.py

@@ -627,11 +627,9 @@ def main():
     except CloudStackException, e:
         module.fail_json(msg='CloudStackException: %s' % str(e))
 
-    except Exception, e:
-        module.fail_json(msg='Exception: %s' % str(e))
-
     module.exit_json(**result)
 
 # import module snippets
 from ansible.module_utils.basic import *
-main()
+if __name__ == '__main__':
+    main()