Preference changes to layouts.

Change-Id: I37366c3465aa1d8d2bd30fb6ae4b821f5f2d5e2d
Additional changes to make the left and right padding
behave the same way as the top and bottom padding.
That is, our default pref screens will automatically
apply the padding and clipToPadding tags. Custom preference
screens will appear as before.
Uses LayoutParams now instead of a specific id.