support for ext4/EMMC in target_files and OTA generation

Move the image sizes into a more generic key-value file.  Make them
optional.  Add additional key/value pairs describing what kind of
filesystem the device uses.  Pass new fs-type-related arguments in
edify scripts when mounting and reformatting partitions.

Don't include all the init.*.rc files from the regular system in
recovery -- they aren't needed, and break recovery on some devices.

Change-Id: I40e49e65f0d76f735259e4b4fef882322cd739da
5 files changed