Remove simplekv requirement, mark as procution instead of beta

Author: vimalloc

setup.py

@@ -17,12 +17,12 @@
       packages=['flask_jwt_extended'],
       zip_safe=False,
       platforms='any',
-      install_requires=['Flask', 'PyJWT', 'simplekv'],
+      install_requires=['Flask', 'PyJWT'],
       extras_require={
         'asymmetric_crypto':  ["cryptography"]
       },
       classifiers=[
-        'Development Status :: 4 - Beta',
+        'Development Status :: 5 - Production/Stable',
         'Environment :: Web Environment',
         'Intended Audience :: Developers',
         'License :: OSI Approved :: MIT License',