Added py37 (#772)

* Added py37 to travis

* Added py37 trove classifier

* Added py37 to tox
diff --git a/setup.py b/setup.py
index 5e80f0c..29c11f4 100755
--- a/setup.py
+++ b/setup.py
@@ -82,6 +82,7 @@
             'Programming Language :: Python :: 3.4',
             'Programming Language :: Python :: 3.5',
             'Programming Language :: Python :: 3.6',
+            'Programming Language :: Python :: 3.7',
 
             'Programming Language :: Python :: Implementation :: CPython',
             'Programming Language :: Python :: Implementation :: PyPy',