This commit add component needed for Optical Character Recognition:
Ocropy, and the patch that need to be applied to make it work with erp5.

The Ocropy egg on Pypi is empty, so this component have to be built from
source. The default neural network model is downloaded from the author
website and installed in python2.7/share/ocropus.

The patch modify how the setup works to allow the C functions in
native.py to be compiled during setup (removing the need to make zope
use gcc) and provide a way to specify the model path for Ocropy.
The patched setup now need to call some modules from different eggs,
whose path needs to be put into sys.path before it can be run.

More models are available here:
https://github.com/tmbdev/ocropy/wiki/Models