'KeyError' exception on cached response, support for pipeline

1. In 'AngularJsonVulnerabilityMiddleware'. In debug mode, when response is not modified (response status code is 304) response doesn't have header 'Content-Type'. It leads to 'KeyError' exception.
2. 'NamespacedAngularAppStorage' can't find path of the files during static collection. This doesn't allow django-pipeline to collect all files into one.
This is due function 'AppStaticStorage.path' takes 'name' with prefix, and search files with that prafix. 
I.e it search  '/home/user/my-site/my_application/app/my_application/js/app.js' instead of '/home/user/my-site/my_application/app/js/app.js'