Added support for compiler proxies

The original issue was raised here - https://bitbucket.org/psam/django-postman/issue/40/postman-with-johnny-cache

And the commit I've based mine on is here - https://github.com/psam44/johnny-cache/commit/08735518261e0749c6aa9a2c7b63b9ef399b6fc0

But 104 commits behind and essentially unusable.