Bug 1030896 - Add ability to dismiss search history items on launch screen

Still a WIP, but an attempt to fix bug 1030896. I stole the swipe listener logic from TabsTray, but removed some things we didn't need. I also updated it to use NOA, which led me to some problems trying to animate the height of the rows. It still doesn't work right... it looks like everything is working correctly, but then after the animation finishes an empty space pops back up in the list. Maybe the problem has to do with the cursor/adapter not actually being updated properly.

I also updated MockHistoryProvider to support deleting items, and to show more items in the list.