reversion 1.9+ support

[Iacopo Spalletti]

Hi all and happy new year everyone, sorry for crossposting, but I think
this might be of interest for both groups: support for django-reversion
1.9+ is feature complete and all tests are passing.
Due the non trivial changes made in the admin it would be of great help
some real-world testing, especially in reverting changes etc.

If anyone is willing to try before merge, the PR is
https://github.com/divio/django-cms/pull/4883

Thanks for helping!

--
Ciao

Iacopo Spalletti