target 3.7 only

Author: edsu

.travis.yml

@@ -1,7 +1,14 @@
 language: python
+
 python:
-  - "2.7"
-  - "3.7"
+- '3.7'
+
+matrix:
+  include:
+    - python: 3.7
+      dist: xenial
+      sudo: true
+
 script: 
   - pip install --upgrade setuptools
   - python setup.py test