modify bayseian setup.py

from #620 . Advise from @garaemon .
It is lib/python2.7/site-packages


> On 2014/12/16, at 10:09, Kei Okada <notifications@github.com> wrote:
> 
> In bayesian_belief_networks/setup.py:
> 
> > @@ -5,7 +5,7 @@
> >  
> >  d = generate_distutils_setup(
> >      packages=['bayesian','bayesian_belief_networks'],
> > -    package_dir={'': get_global_python_destination(),'bayesian_belief_networks':'src'}
> what get_global_python_destinatino() returns.
> 
> \
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>