switching to testing 3.7dev

Author: fcollman

.travis.yml

@@ -2,9 +2,9 @@ language: python
 python:
   - "2.7"
   - "3.5"
-  - "3.5-dev" # 3.5 development branch
   - "3.6"
   - "3.6-dev" # 3.6 development branch
+  - "3.7-dev"
 services:
   - docker
 # command to install dependencies