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
envsetup: Set CUSTOM_BUILD environment variable

This is used to gate a few features, including backuptool

Change-Id: I02fee9e0765cca88c833bb0514762aa3b14642e3
envsetup: add a helper to fix "out/target/common" not being really common

* out/target/common isn't really common, and if you do
  back to back builds for multiple devices, that is noticable.
* Use out/target/common-$device instead, and link the appropriate
  dir to out/target/common every time lunch() is run, if
  ANDROID_FIXUP_COMMON_OUT is set.
* Refer https://groups.google.com/forum/#!topic/android-building/ispbOgzoyg8
  for more info.

Change-Id: I11e7df0e68e2a60ce32576f06397d60fc9465b60
Update to MintKat.