Allow properties to be derived from partition-specific properties

This change allows ro.product.[brand|device|manufacturer|model|name] and
ro.build.fingerprint to be derived at boot time (and in the OTA
generation scripts) from partition-specific properties.

Test: booted system image, verified properties
Test: booted recovery image, verified properties
Test: unpacked OTA package, verified build fingerprint
Bug: 120123525
Change-Id: Iadd230a0577f35c7c37b0f911e91a5c2863ed1fe