ota: Validate any installed data's signature against our own

Try to prevent incompatible-signature system quirkiness

Change-Id: I73402d963a1b57ad0ee3c68ced4f2d7f074f927f
(cherry picked from commit aff5e54c4ef5fec7e67e830f83ee64424005d07c)
common: Set property for the CM releasetype

Set ro.cm.releasetype based on the deteremined releasetype of the
build.

Change-Id: I2c1aa7181f42342594bd6d5dc5f5252220ed3497
(cherry picked from commit af917582107903d6544b2a4c78e310f848379600)

Conflicts:
	config/common.mk