Force hw rendering & Dalvik changes

* Force hardware acceleration (needed to enable highend effects on
  devices with <512MB ram)
* Dalvik: disable JIT (uses too much RAM for a 256MB device)
* Dalvik: increase heapsize & heapgrowthlimit, to avoid excessive
  garbage collection

Change-Id: I4353abead7f7470c6444aeffe133754526806242