Fix reversion issues

Fix (or try to) reversion. The problem is:

The production env has two versions of the module 'reversion', one installed by pip, and other on the lib.reversion. We are registering models on one, and calling the middleware on the other. 
This fixes the imports, but the pip's verison should be uninstalled. 


## IMPORTANT

1) Before deploying please revmove the "reversion" module from ou virtualenv, thats probably whats is causing the issue.

2) someone please test this on an working env. I've testes on shell and seems to work, but I can't fix my project environment right now.