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)
PS 2: Any device can use hwa by Setting ro.sys.force_full_hwa to true inside the build.prop, original AOSP requirements stay intact
PS 3: Style