update .travis.yml file

.travis.yml

 language: python
 python:
-  - "2.7"
-  - "3.4"
-  - "pypy"
+  - "3.6"
 # command to install dependencies
 install:
   - pip install python-dateutil
   - pip install pytz
   - pip install lxml
-  - if [[ $TRAVIS_PYTHON_VERSION == '3.4' ]]; then pip install cryptography ; fi
-  - if [[ $TRAVIS_PYTHON_VERSION == '2.7' ]]; then pip install futures ; fi
-  - if [[ $TRAVIS_PYTHON_VERSION == '2.7' ]]; then pip install cryptography ; fi
-  - if [[ $TRAVIS_PYTHON_VERSION == '2.7' ]]; then pip install trollius ; fi
-  - if [[ $TRAVIS_PYTHON_VERSION == '2.7' ]]; then pip install enum34 ; fi
-    #- if [[ $TRAVIS_PYTHON_VERSION == 'pypy3' ]]; then pip install cryptography ; fi
-  - if [[ $TRAVIS_PYTHON_VERSION == 'pypy' ]]; then pip install futures ; fi
-  - if [[ $TRAVIS_PYTHON_VERSION == 'pypy' ]]; then pip install trollius ; fi
-  - if [[ $TRAVIS_PYTHON_VERSION == 'pypy' ]]; then pip install enum34 ; fi
+  - pip install aiofiles
+  - pip install asyncio-contextmanager
+  - pip install pytest
+  - pip install cryptography
 # command to run tests
-script: ./run-tests.sh
+script: pytest -v