80% of the way converted over to json based config

- The arm has no more hard coded percentages
- The arm has switched to pwm usecs
- The arm doesn't care about forward/backward it just knows the target values
- We can read in the json config file
- We can partially write it out
- The pwm is responsible for its own config (this isn't done yet though)
- The pmssc can handle setting duty values before it is connected
- The nervous system will set each pwm to middle value before connecting