Handle screenSize configuration change to avoid Activity restarts.

I'm not sure if we should sneak this into 2.0.2 or leave it for the next version. Let me know if you want this retargeted.

Our activities are restarting on rotation in Android 3.2+. See [Issue 1845](https://code.google.com/p/ankidroid/issues/detail?id=1845) for an example of a problem this causes. 

By default, activities are restarted on Android when a configuration changes and isn't handled. AnkiDroid chooses to handle (and ignore most of) them to avoid these restarts. The [Android documentation](http://developer.android.com/guide/topics/resources/runtime-changes.html#HandlingTheChange) tells us that yet another configuration item was added for screen rotation in 3.2, and we aren't handling it, so our activities restart.

This change adds this configuration to the list and stops activities from restarting.