Added the Method to Update the User

lib/Users.js

@@ -100,6 +100,30 @@ const Users = {
         new User(client, json, ip_address, fingerprint, callback);
       }
     });
+  },
+
+  /** Update a user - Calling the Patch on User
+   * @param client [Object]
+   * @param fingerprint [String] : the device that is trying to access a user's information
+   * @param ip_address [String] : ip address of user
+   * @param payload [Object] : Look at docs for format (https://docs.synapsepay.com/docs/create-a-user)
+   * @param userID [String] : User Object ID
+   * @param callback [function(error, userResponseObj)]
+   **/
+  update(client, fingerprint, ip_address, payload, userID, callback) {
+    const config = {
+      client: client,
+      fingerprint: fingerprint,
+      ip_address: ip_address
+    };
+    const url = client.baseUrl + '/users/' + userID;
+    APIClient.patch(url, config, payload, (err, json) => {
+      if (err) {
+        callback(err);
+      } else {
+        new User(client, json, ip_address, fingerprint, callback);
+      }
+    });
   }
 };