jfltevzw: Support potential dev phones

Add support for phones with unlocked boot loaders that do not
require Loki.  Current implementation will not install a boot
image at all unless the phone is a known Loki phone.  This alters
the behavior to flash a stock boot image when we know the
boot loader supports it.

Change-Id: I7e58a883238782f298dc14bb73ea0b1a5b71af96