Try to set up testing on python 3.7 allow failures so if it tanks the

whole build doesn't fail.

Author: rouilj

.travis.yml

@@ -1,10 +1,17 @@
 language: python
-python:
-  - 2.7
-  - 3.4
-  - 3.5
-  - 3.6
-  # - 3.7 not available in travis with 14.04 ubuntu base.
+
+matrix:
+  include:
+    - name: "Python <=3.6"
+      python:
+        - 2.7
+        - 3.4
+        - 3.5
+        - 3.6
+  allow_failures:
+    - name: "Python >3.6"
+      python: 3.7
+      dist: xenial
 
 sudo: false