Add Python 3.7 to classifiers

Author: tony

setup.py

@@ -67,6 +67,7 @@ def run_tests(self):
         'Programming Language :: Python :: 3.4',
         'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: 3.7',
         'Programming Language :: Python :: Implementation :: PyPy',
         "Topic :: Utilities",
         "Topic :: System :: Shells",