hammerhead: Add mpdecision to system group

File ownership is set by ueventd. Upstream commit:
bf8fcfa71fd365add34a394cbe38828ce8a558fb

Change-Id: I7e67f6aafce876b07a099120aa1bc760ab254d20
releasetools: Don't assert an included bootloader

If we are including a bootloader with the update, do not require it
for the OTA since it will be updated with the package.

Change-Id: I074f132925974b1164185294ecfd35e37c6c3972
hammerhead: Use QCOM PowerHAL

Change-Id: Ia40f84d2eb511dd1c7c0521706422ddf68e51342