[IMP] replace PIL dependency by pillow

pillow is a better-maintained fork, and installing it from source
tends to succeed more easily than PIL's

bzr revid: xmo@openerp.com-20140114131032-rxwpmc0yrqp91x4v

setup.py

@@ -125,7 +125,7 @@ setuptools.setup(
           'lxml', # windows binary http://www.lfd.uci.edu/~gohlke/pythonlibs/
           'mako',
           'mock',
-          'PIL', # windows binary http://www.lfd.uci.edu/~gohlke/pythonlibs/
+          'pillow', # windows binary http://www.lfd.uci.edu/~gohlke/pythonlibs/
           'psutil', # windows binary code.google.com/p/psutil/downloads/list
           'psycopg2 >= 2.2',
           'pydot',