Fix bugs in servo_control.c

Align the MemoryPool storage arrays.

Make sure to lock the system and use I-class API functions in the
set_pwm_position function, which is invoked from an interrupt context.

Send the debug positions in PositionCommand structs.
Tweak flight-servo's host-fc servo_test.c

Explicitly sleep in main, rather than having sendpwm handle it.
Add some printf logging for visibility.
Delete some commented code.
Change the limits on the sent payload data.
servo_control uses direct packet position value.

Additionally, free any PositionDeltas received back from the
set_pwm_position command.

Also, move socket initialization into the else arm of the #if DEBUG_PWM
preprocessor conditional.