Add scipy to travis requirements--some unit tests require this

.travis.yml

@@ -51,7 +51,7 @@ install:
     - conda update conda --yes
     - conda create -n test_env python=${PYTHON} --yes
     - source activate test_env
-    - conda install numpy pyopengl pytest flake8 six coverage --yes
+    - conda install numpy scipy pyopengl pytest flake8 six coverage --yes
     - echo ${QT}
     - echo ${TEST}
     - echo ${PYTHON}