installclean: remove *.md5sum

Change-Id: Iba47421324bd6bbeabaa80eb66daf6a25621d6a2
unpackbootimg: add a target specifically for unpackbootimg

Change-Id: I8c71a56505d155f43d0776074c09404ce6f6d34b
build: Add unpackbootimg to dist_tools

Change-Id: I58622b8f0a85db18fabdc2cf96d11c5982a9c9d8
Add ifeq flag to MINIGZIP for devices like tf101

that can not use lzma to compress the kernel without causing problems
but can not compile a recovery without a compression like lzma
BOARD_NEEDS_LZMA_MINIGZIP := true

Change-Id: I0cb8b126234fc5d20ceee83c2eb0266c37e4ff0f