Needed for receipt_recognition module. It contain the ocropy library and its binarization, segementation and recognition tools, as well as the scipy library containing the ndimage and stats module used in receipt_recognition_module for the binarization and inside ocropy.

This is separated in 3 commits: The first one add ocropy and dependancies inside slapos component; The second one add the ocropy component to stack/erp5 buildout config file, and add gcc to the binaries callable from erp5 (needed by ocropy); The third is only required for the module to work without installing the wendelin software.

Edit: To keep discussions posts, i wont rebase in master, to see the rebased final commits: https://lab.nexedi.com/francois.lecorre/slapos/commits/rebased_branch