convert bash to python for the bootzip creator script

PS4: added fstab check and some cleanup

Change-Id: Icff7d5ac7e2b442f1ffe5c4c11e02aa0b18333f3
boot_flash_from_image: Strip kernel modules

Change-Id: I36168705cc71d10e1d9a4613207660d5bbf167b8
boot_flash_from_image: A little tune up

Change-Id: Ie8a46eaa44ea35882bcc3d5aa8adf2df9bae5949
bootzip: pass BOOT_ZIP_OUT_FILE and create md5 file

Change-Id: I2da8e5898240e9d57219d936c2f260205108fa53