add 1rst version of travis config

.travis.yml

+sudo: false
+language: python
+python:
+  - "3.4"
+  - "3.5"
+  - "3.6"
+
+install:
+  - pip install --upgrade pip setuptools
+  - pip install -e ".[testing]"
+
+script: pytest
+
+after_success:
+  - coveralls