v1.3.0a4

Adds ASGI support via #147 so RequestEvent will work on WSGI and ASGI. async views (async def, not async as in "asgi") are not explicitly tested at this time. The changes made were in the signal handler and the middleware (the middleware will function correctly in ASGI and WSGI -- it does not support async at this time, which django is fine with no matter what). Should your view be run via async, please test ahead of time and we should be able to support that use case (if things break).