Run tests with pytest on TravisCI

Install pytorch with conda. Most of .travis.yml copied from the example
provided by the conda folks at:

https://conda.io/docs/travis.html

.travis.yml

 language: python
-python: 2.7
+python:
+  - "2.7"
+  - "3.5"
 
-install: pip install flake8
-script: flake8
+install:
+  - sudo apt-get update
+  - wget https://repo.continuum.io/miniconda/Miniconda3-latest-Linux-x86_64.sh -O miniconda.sh;
+  - bash miniconda.sh -b -p $HOME/miniconda
+  - export PATH="$HOME/miniconda/bin:$PATH"
+  - hash -r
+  - conda config --set always_yes yes --set changeps1 no
+  - conda update -q conda
+  # Useful for debugging any issues with conda
+  - conda info -a
+
+  - conda create -q -n test-environment python=$TRAVIS_PYTHON_VERSION pytorch -c soumith
+  - source activate test-environment
+  - python setup.py install
+  - pip install --upgrade pytest
+
+script:
+  - pytest test/
+
+matrix:
+  include:
+    - env: LINT_CHECK
+      python: "2.7"
+      install: pip install flake8
+      script: flake8

README.rst

 torch-vision
 ============
 
+.. image:: https://travis-ci.org/pytorch/vision.svg?branch=master
+    :target: https://travis-ci.org/pytorch/vision
+
 This repository consists of:
 
 -  `vision.datasets <#datasets>`__ : Data loaders for popular vision