fix: conda install without prompt

Author: satra

.travis.yml

@@ -26,7 +26,7 @@ before_install:
 install:
   - conda create -n testenv --yes pip python=$TRAVIS_PYTHON_VERSION
   - source activate testenv
-  - conda install numpy scipy nose traits networkx dateutil
+  - conda install --yes numpy scipy nose traits networkx dateutil
   - pip install nibabel --use-mirrors
   - pip install python-coveralls --use-mirrors
   - pip install nose-cov --use-mirrors