Fix: DoubleNumberPickerPreference was switching the default values

Change-Id: I8848af2c0c1af895370592d11aa3d99724db4b46
Adjust left and right paddings for TabletUI
In tablet ui, the launcher should have an extra padding in both sides so it looks more like stock launcher

Change-Id: Ic21accab28535f30aa5e02427c6a74d5c50d6dfd
Remove stretch screens preference
This option was useless since the screens always get stretched.

Change-Id: Icd203da90e128647d1073a9942998cb031f5ebb1