Adding support for importing models through the app registry while it is loading

Hello, Since Django 1.7, `get_user_model()` cannot be called at import time. Django contains a lot of methods that start with `UserModel = get_user_model()` while it would be more natural to declare it as a global variable in the module. This trips up users and the reason why it’s forbidden isn

Re: Exceptions caught by the "include" template tag make it hard to rely on tests

> Has anyone relied on the exception silencing behavior as a "feature" when using {% include %}? Not here. +1 on deprecating the silencing behavior. I have created a ticket [0] and PR [1] so others may get a sense of the bigger picture change and how it could affect Django. Feedback welcome. Mo