enable zram kitkat style

Use 64MB (~16%) zRAM size.

http://source.android.com/devices/low-ram.html#zram

Previous zRAM implementation was removed from CM11.
http://review.cyanogenmod.org/#/c/56874/
http://review.cyanogenmod.org/#/c/56875/

Change-Id: I3c5f2eb25ff1a6851326c5d09eacf19e4a25ade1