releasetools: support more partitions and different fstab types

* add BML support for Samsung legacy devices
* add ext2, ext3 and vfat, f2fs support for EMMC
* fix recovery.fstab for ADV recovery

Change-Id: I6b76d2a21fe68096cf1b0cd850cdfb3a313370d1
build: work around missing readlink -f on Mac

Change-Id: I5d56366cf33a2b02f1886c87815d00cff279779d
repopick: Add a way to checkout instead of cherrypick

This helps if you want to take a commit and its dependencies, and not
just a particular commit

Change-Id: Ib245cce560c7b0d6fd03198a8c69a13d4720a4cb