Passed History state differently in Forum

Hopefully resolves #1034.

http://jenkins.buttonweavers.com:8080/job/buttonmen-AdmiralJota/237/

I can't test this myself, since I don't have an affected device. Could someone who does have a pre-4.2 Android device try this out and see if it does fix the problem? (Both that you can view the forum, and that after you've clicked through to a board/thread a couple times, that the back button works as expected.)