Configure dalvik heap parameters for low memory devices

Reduces after boot memory footprint by about 5-8MB
Note: This is for low memory based devices only (~512MB RAM
or less)

Change-Id: I4b4b9ae3efaff96551457e566bbb9bd4f0f23fd5
Merge remote-tracking branch 'CyanogenMod/cm-10.1' into cm-10.1