added python3.6 on tox (#3749)

tox.ini

@@ -1,7 +1,7 @@
 [tox]
 envlist =
-    {2.7,pypy,3.4,3.5}-unit
-    {2.7,pypy,3.4,3.5}-integration-{rabbitmq,redis}
+    {2.7,pypy,3.4,3.5,3.6}-unit
+    {2.7,pypy,3.4,3.5,3.6}-integration-{rabbitmq,redis}
 
     flake8
     flakeplus
@@ -15,7 +15,7 @@ deps=
     -r{toxinidir}/requirements/test.txt
 
     2.7: -r{toxinidir}/requirements/test-ci-default.txt
-    3.4,3.5: -r{toxinidir}/requirements/test-ci-default.txt
+    3.4,3.5,3.6: -r{toxinidir}/requirements/test-ci-default.txt
     pypy: -r{toxinidir}/requirements/test-ci-base.txt
 
     integration: -r{toxinidir}/requirements/test-integration.txt
@@ -40,6 +40,7 @@ basepython =
     2.7: python2.7
     3.4: python3.4
     3.5: python3.5
+    3.6: python3.6
     pypy: pypy
     flake8,flakeplus,apicheck,linkcheck,configcheck,pydocstyle: python2.7