Lock on custom admin with custom key

[kutera]

Hi, Thanks for this package, really usefull and simple to install. On my project, I use UUID key instead of integer, with a custom admin site. The url and model structures crashed with your version. So I suggest some modifications in order to work with admin and integer key, and other kind of django key and admin.

I added french translations.

Best Regards Jean

[joshmaker]

Thanks for the PR Jean, however I want to get tests passing before I look at this in-depth. I think the test failures might be due to changes in Travis and not your code, so I'll try to take a look today.

[kutera]

Some migrations were missing. I added it.