Add support for Python 3.7

This change adds official library support for Python 3.7, including
updating the testing infrastructure for both tox and Travis CI and
updating the library package metadata in setup.py.

.travis.yml

@@ -146,6 +146,42 @@ matrix:
           os: linux
           dist: xenial
           env: TOXENV=py36 RUN_INTEGRATION_TESTS=2
+#        - python: 3.7
+#          os: linux
+#          dist: precise
+#          env: TOXENV=py37 RUN_INTEGRATION_TESTS=0
+#        - python: 3.7
+#          os: linux
+#          dist: trusty
+#          env: TOXENV=py37 RUN_INTEGRATION_TESTS=0
+        - python: 3.7
+          os: linux
+          dist: xenial
+          env: TOXENV=py37 RUN_INTEGRATION_TESTS=0
+#        - python: 3.7
+#          os: linux
+#          dist: precise
+#          env: TOXENV=py37 RUN_INTEGRATION_TESTS=1
+#        - python: 3.7
+#          os: linux
+#          dist: trusty
+#          env: TOXENV=py37 RUN_INTEGRATION_TESTS=1
+        - python: 3.7
+          os: linux
+          dist: xenial
+          env: TOXENV=py36 RUN_INTEGRATION_TESTS=1
+#        - python: 3.7
+#          os: linux
+#          dist: precise
+#          env: TOXENV=py37 RUN_INTEGRATION_TESTS=2
+#        - python: 3.7
+#          os: linux
+#          dist: trusty
+#          env: TOXENV=py37 RUN_INTEGRATION_TESTS=2
+        - python: 3.7
+          os: linux
+          dist: xenial
+          env: TOXENV=py37 RUN_INTEGRATION_TESTS=2
         - python: 2.7
           os: linux
           dist: precise

setup.py

@@ -60,5 +60,6 @@ setuptools.setup(
         "Programming Language :: Python :: 3.4",
         "Programming Language :: Python :: 3.5",
         "Programming Language :: Python :: 3.6",
+        "Programming Language :: Python :: 3.7",
     ],
 )

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = pep8,py27,py34,py35,py36,bandit,docs
+envlist = pep8,py27,py34,py35,py36,py37,bandit,docs
 
 [testenv]
 passenv = TRAVIS TRAVIS_JOB_ID TRAVIS_BRANCH