Lower the RAM requirement for hardware acceleration

There are legacy devices with about 365 MBytes of RAM
available to the kernel (HDPI with 512 MB RAM onboard).
Lowering the requirement value for available RAM allows
these devices to also use hardware acceleration, thus
making the UI a lot more responsive and fixing bugs like
this: https://dl.dropboxusercontent.com/u/16268774/Screenshots/Phone/Screenshot_2013-10-07-01-27-45.png
(notice the "shadow" is missing)

Change-Id: I0343ddbb3c7f95bed674b5852772ab819065ea69

PS 2: Redo hardware acceleration requirements
Enable Full HWA with ro.sys.force_full_hwa via System properties

PS3: Underp