Add travis config.

.travis.yml

@@ -0,0 +1,10 @@
+language: python
+python:
+  - "3.5"
+  - "3.6"
+  - "3.7-dev"  # 3.7 development branch
+install:
+  - pip install -r requirements.txt
+# command to run tests
+script:
+  - pytest