add: demo server and client

demo_server/openapi_server/__main__.py

@@ -0,0 +1,19 @@
+#!/usr/bin/env python3
+
+import connexion
+
+from openapi_server import encoder
+
+
+def main():
+    app = connexion.App(__name__, specification_dir='./openapi/')
+    app.app.json_encoder = encoder.JSONEncoder
+    app.add_api('openapi.yaml',
+                arguments={'title': 'PeerNetService API'},
+                pythonic_params=True)
+
+    app.run(port=8080)
+
+
+if __name__ == '__main__':
+    main()