[MANIFEST.in] Include .json files from data folder

Holds a .json annotations sample.

MANIFEST.in

 include README.rst bootstrap-buildout.py buildout.cfg develop.cfg LICENSE version.txt requirements.txt
 recursive-include doc *.py *.rst
-recursive-include bob/bio/face/test/data *.hdf5 *.jpg *.pos *.png
+recursive-include bob/bio/face/test/data *.hdf5 *.jpg *.pos *.png *.json