make error reporting layout fill properly on small screns

*Could go in either 2.1 or 2.2 I guess since it's a bug not a feature.*

Fix [Issue 2027](https://code.google.com/p/ankidroid/issues/detail?id=2027): 	Issues with crash reporter screen on 320x240:

I embedded the Disclaimer text in the error reporter in a ScrollView, so that the disclaimer shrinks if the screen is too small... I couldn't get it to behave as expected using the existing RelativeLayout, so I changed to a LinearLayout.