Find7: cleanup ramdisk and restructure

Based off Hammerhead's kitkat ramdisk

Should fix various issues like device heating on
boot, external SD card not being mounted et cetera.

PS #2: Switch to bone stock hammerhead governor values
PS #3: Finalize governor edits to hammerhead stock
PS #4: Add mount.exfat and remove one last line
PS #5: add back device specific bits to ueventd

Change-Id: I3e646541a70a0bf6cdd54ebb872ba4418da6bb5a