Merge pull request #6 from bioidiap/netpbm

.travis.yml

bob/io/image/data/test_2.pgm

bob/io/image/data/test_2.ppm

bob/io/image/netpbm.cpp

bob/io/image/pnmio.c

bob/io/image/pnmio.h

bob/io/image/test.py

bob/io/image/version.cpp

doc/links.rst

setup.py