install torch via pip

.travis.yml

@@ -7,10 +7,12 @@ matrix:
     - python: 3.5
     - python: 3.6
 install:
+  - if [[ $TRAVIS_PYTHON_VERSION == 2.7 ]]; then pip install --quiet http://download.pytorch.org/whl/cpu/torch-0.3.1-cp27-cp27mu-linux_x86_64.whl; fi
+  - if [[ $TRAVIS_PYTHON_VERSION == 3.5 ]]; then pip install --quiet http://download.pytorch.org/whl/cpu/torch-0.3.1-cp35-cp35m-linux_x86_64.whl; fi
+  - if [[ $TRAVIS_PYTHON_VERSION == 3.6 ]]; then pip install --quiet http://download.pytorch.org/whl/cpu/torch-0.3.1-cp36-cp36m-linux_x86_64.whl; fi
   - pip install pycodestyle
   - pip install flake8
   - pip install codecov
-  - pip install torch
   - pip install cffi
 script:
   - pycodestyle .