zRAM: enable, enhance & allow coexistence with SD swap

* Using Jellybean method to activate zRAM, as etc script would
  interfere with the KitKat method
* Modify GalaxyParts to allow zRAM and regular swap to coexist
* Tune /proc/sys/vm/page-cluster to 0 (as recommended for KitKat)
* Set zRAM on by default (18% for Froyo device, 26% for Gingerbread)

Change-Id: Ic60164baccdd7839744131feb82bacce399203bb