- avbtool only works with python 2.x, so systems which only have python
3.x as default will fail to run avbtool, fix it
- avbtool: sync with AOSP master
- avb salt: store salt for AVB signature, and use it in re-packing process
- ramdisk gzip: java.util.zip.GZIPOutputStream doesn't support parameters, so we use
org.apache.commons.compress.compressors.gzip.GzipCompressorOutputStream instead
cfig