aries-common: use KitKat zRAM setting

CM's compcache has been removed, so we need to migrate to KitKat's
mechanism. The value is set to 64 MB for now, which is approximately
equal to the old 18% setting.

PS: nuked old zram stuff

Change-Id: Ib780aed8c336cea5baf0f672e41179ef85790061