Patch for #18924
Updated Pavel Ponomarev's patch (pull request #322) to work with custom user models
Fixed #18924 -- Made test.Client.logout send user_logged_out signal.
Thanks Pavel Ponomarev for the initial patch
refactor to take advantage of default logout()
Remove unneeded session.delete.
remove unused import
made tests work with custom user models
I've updated the patch to apply without merge conflicts after regressiontests and modeltests got merged into test root.
merged in a35ed20, thanks!