Parse mtree files into a file tree dictionary with checksums and file sizes
run mtree as:
`mtree -c -K md5digest -p test_tree/ > mtree_test.spec`

mtree is BSD but is available for linux through http://code.google.com/p/mtree-port/ and other ports.
You'll need to get openssl:
`sudo apt-get install openssl libssl-dev`