fix python 3.4/3.5 and remove duplicate builds (#6)

* fix python 3.4/3.5 and remove duplicate builds

* add python 3.7

* switch to xenial

Author: ewhauser

.travis.yml

@@ -1,10 +1,12 @@
 language: python
-sudo: false
+sudo: required
+dist: xenial
 python:
 - 2.7
 - 3.4
 - 3.5
 - 3.6
+- 3.7
 install:
 - |
   if [ "$TEST_TYPE" = build ]; then
@@ -41,11 +43,9 @@ matrix:
     env: TEST_TYPE=build
   - python: '3.6'
     env: TEST_TYPE=build
-  - python: '3.5'
-    env: TEST_TYPE=build
-  - python: '3.6'
+  - python: '3.7'
     env: TEST_TYPE=build
   - python: '2.7'
     env: TEST_TYPE=lint
-  - python: '3.6'
+  - python: '3.7'
     env: TEST_TYPE=lint

graphene_tornado/tests/test_graphql.py

@@ -553,4 +553,4 @@ def batch_url_string(**url_params):
 
 
 def response_json(response):
-    return json.loads(response.body)
+    return json.loads(to_unicode(response.body))