Test more python versions on travis CI

It seems tests weren't correctly run because of interactions between
travis CI env and tox venv.  Also, run the scenario test on more
recent python3, as python3.4 is going away.
The test uses a lot of memory and fails with pypy, so it's disabled for now.

Signed-off-by: IWAMOTO Toshihiro <iwamoto@valinux.co.jp>
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>

.travis.yml

@@ -1,14 +1,31 @@
 language: python
-python:
-  - "3.5"  # Python 3.5 still needs to be installed on Travis-CI
 
-env:
-  - TOX_ENV=py27
-  - TOX_ENV=py34
-  - TOX_ENV=py35
-  - TOX_ENV=pypy26
-  - TOX_ENV=pycodestyle
-  - TOX_ENV=autopep8
+matrix:
+  include:
+    - python: 3.6
+      env: TOX_ENV=pycodestyle
+    - python: 3.6
+      env: TOX_ENV=py36
+    - python: 3.6
+      env: TOX_ENV=autopep8
+
+    - python: 2.7
+      env: TOX_ENV=pycodestyle
+    - python: 2.7
+      env: TOX_ENV=py27
+
+    - python: 3.4
+      env: TOX_ENV=py34
+
+    - python: 3.5
+      env: TOX_ENV=py35
+
+    - python: 3.7-dev
+      env: TOX_ENV=py37
+
+# This is disabled because of trouble running on travis CI.
+#    - python: pypy
+#      env: TOX_ENV=pypy
 
 services:
   - docker

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = py27,py34,py35,pypy26,pycodestyle,autopep8
+envlist = py27,py34,py35,py36,py37,pypy,pycodestyle,autopep8
 
 [testenv]
 deps =
@@ -25,7 +25,7 @@ commands =
   {[testenv]commands}
   {[testenv:scenario]commands}
 
-[testenv:py34]
+[testenv:py36]
 commands =
   {[testenv]commands}
   {[testenv:scenario]commands}