bump test app to most recent Houston version
add custom template tests to test_app
custom templates: change routing

* add /custom to the route so it doesn't conflict with the collection
  routes
* Move route up so it has higher "priority" than collection route
* make the links match the new route
change the custom templates path prefix to "actions"
Merge pull request #265 from wfleming/fix-custom-templates

Fix custom templates (issue #256)