build gpsshim

Builds gpsshim to load the old gps lib for buzz.
Make sure to include
<project name="Evervolv/android_hardware_gpsshim"
 path="hardware/gpsshim" remote="github" />
in the local_manifest.xml.

Change-Id: I8e4ce04763571014e279d20acdb833c322d984db
system.prop: remove "tweaks"

Removes some system.prop tweaks that actually have no effect, see
http://www.jeffmixon.com/examining-build-prop-tweaks-for-android-ics-a-comprehensive-guide-part-1/