Enable KitKat-style zRAM support by default

* Enable 48MB (Gingerbread) / 32MB (Froyo) zRAM allocation
* Modify GalaxyParts to allow zRAM & regular swap coexistence
* Set swap priorities: 0 for regular swap, 1 for zRAM

Change-Id: I3df810ec4abb4146b907cf9ae1231e75e111684a