Move TARGET_SCREEN_WIDTH/HEIGHT to the right place

Just about every other device defines these two variables in cm.mk
before including a common configuration from vendor/cm, which ensures
that they don't pull in a default boot animation.
Use half-resolution version of the boot animation for better performance
 Remove libskia_legacy from build

Android 4.4's browser no longer supports the saved pages feature, so
this is no longer useful.
Use 120Mb ZRAM by default
Fixed typo and format style