update to py3.6 on Travis

Author: msarahan

.travis.yml

@@ -2,17 +2,17 @@ language: python
 matrix:
   fast_finish: true
   include:
-    - python: '3.5'
+    - python: '3.6'
       env:
         - FLAKE8=true
       os: linux
     - python: '2.7'
       env: $CONDA_VERSION=4.2.x
       os: linux
-    - python: '3.5'
+    - python: '3.6'
       env: $CONDA_VERSION=4.2.x
       os: linux
-    - python: '3.5'
+    - python: '3.6'
       env: $CONDA_VERSION=4.3.x
       os: linux