Adds longer default timeout to heat stack-create call

Tuskar-UI currently uses the default stack timeout in heat which is
60 minutes.  The CLI defaults the stack timeout to 240 minutes.
This patch adds the timeout_mins paramater set to 240 to match the
same behavior as the CLI.

Change-Id: I983db9218e43020235c54856ca6b435ebc33400b

tuskar_ui/api/heat.py

@@ -141,6 +141,7 @@ class Stack(base.APIResourceWrapper):
             'template': template,
             'environment': environment,
             'files': files,
+            'timeout_mins': 240,
         }
         password = getattr(settings, 'UNDERCLOUD_ADMIN_PASSWORD', None)
         stack = heat.stack_create(request, password, **fields)