Add example of middleware usage

Author: tedeh

examples/middleware/server.js

@@ -0,0 +1,15 @@
+var jayson = require(__dirname + '/../..');
+var connect = require('connect');
+var app = connect();
+
+var server = jayson.server({
+  add: function(a, b, callback) {
+    callback(null, a + b);
+  }
+});
+
+// parse request body before the jayson middleware
+app.use(connect.bodyParser());
+app.use(server.middleware());
+
+app.listen(3000);