Addtion new function and any bug fix

The new function

1. Add function getCurrentReturnDelay()
2. Add function saveFlashRom()

Bug fix

2. changeServoId
   Wrong calc packet header size

Fix a bug #1

This release bug fix about issue#1
#1

Implements function of setMaxTorque method

This version adding new function that name is setMaxTorque.
The function set max torque to the Servo. That mean you can controll compliance of Servo.

Implements full function

Implements full function of controll servo.