Update development status to 'Production/Stable' (#127)

Author: StanFromIreland

setup.cfg

@@ -12,7 +12,7 @@ license_files =
     LICENSE
     licenses/LICENSE_APACHE
 classifiers =
-    Development Status :: 4 - Beta
+    Development Status :: 5 - Production/Stable
     Intended Audience :: Developers
     Programming Language :: Python :: 2
     Programming Language :: Python :: 3