d2-common: clean up fstab

Change-Id: I104303c1318008fbdc4344e527dec1a749a3da9f
d2-common: update startup scripts for 4.3

Patch set 2: rebased
Patch set 3: added a missing bit, and reverted changes to dhcpd_bnep0
that broke bt tethering

Change-Id: I31efbc59be7faf0fde595e55f6647101ea392841