Settings : isScreenLarge rewrite

Mimick how framework decides on screen layout to differentiate
tablets from phones.

Patchset 2 - Cleanup imports
Patchset 3 - Make the check more explicit
Patchset 4 - Rename isScreenLarge to getScreenSize

Change-Id: Icd90798ee7de62f5a1997820046608ea27e7835e

Conflicts:
	src/com/android/settings/cyanogenmod/SystemSettings.java
fix

Change-Id: I3f3faff7b33e16b1726d5ebe6a9cc99eaf70eaaf