Flight-Servo: Feature Complete

[ThirteenFish]

This is an issue created specifically for Alpha 2

Major features:

• Respond to version command.
• Actuate servo in response to servo packets.
• Limit servo to soft stops when built for flight, also limit rate of change in dev.
• Respond with an error packet if it cant set the requested value, and what value it set it to.
  • It should respond with the sequence number of the offending packet, and that it couldn't do as requested. Once the servo moves to either the soft stop or rate limited position it should notify the FC it is there. In the built for flight case this means it only notifies when it hits a soft stop, and since it's not rate limited, can be in the initial error response.