Pin NumPy and SciPy to versions in the wheelhouse.

Matplotlib 1.3.1 and NumPy 1.9.0 are incompatible (so it surprises me
that they'll both install), and cause test failures.

.travis.yml

@@ -12,7 +12,7 @@ before_install:
   - pip install --upgrade setuptools
   - pip install wheel
   - wget -q -O - 'https://github.com/obspy/wheelhouse/archive/master.tar.gz' | tar -C /tmp -xzf -
-  - pip install --use-wheel --no-index --find-links=/tmp/wheelhouse-master numpy scipy lxml sqlalchemy m2crypto mock nose
+  - pip install --use-wheel --no-index --find-links=/tmp/wheelhouse-master numpy==1.8.1 scipy==0.14.0 lxml sqlalchemy m2crypto mock nose
   - pip install --use-wheel --find-links=/tmp/wheelhouse-master coveralls
   - pip install --use-mirrors geographiclib
   - pip install --use-wheel --no-index --find-links=/tmp/wheelhouse-master matplotlib==1.3.1