Merge pull request #690 from glennpj/py_updates

var/spack/repos/builtin/packages/py-bottleneck/package.py

var/spack/repos/builtin/packages/py-dateutil/package.py

var/spack/repos/builtin/packages/py-matplotlib/package.py

var/spack/repos/builtin/packages/py-nose/package.py

var/spack/repos/builtin/packages/py-numexpr/package.py

var/spack/repos/builtin/packages/py-numpy/package.py

var/spack/repos/builtin/packages/py-pandas/package.py

var/spack/repos/builtin/packages/py-pytz/package.py

var/spack/repos/builtin/packages/py-setuptools/package.py

var/spack/repos/builtin/packages/py-six/package.py

var/spack/repos/builtin/packages/py-virtualenv/package.py