Not working during testing

[denyswsu]

First of all I want to thank you for this library!

But the problem I faced was that it didn't work in my tests, I spend about a day to find the issue and resolve it.

So just after browsing the source code I realized that TEST = True needs to be set in django settings for it to work, because otherwise it's called after transaction is finished (which is not the case inside test method).

Leaving it here for people who will face same problem, or let's add it to README/wiki?