Changed fail response, slowed spline calc, longer "send to..." accel/decel

--When sending a failure response, the MoCoBus protocol now sends a 2
instead of a 0. This is to help differentiate dropped packets (i.e. com
errors) from actual failure responses.
--Motor movement splines are now calculated ever 20ms instead of 10 ms.
Slowing this down drastically improved BTLE communication stability.
--move() function was modified slightly to allow for different
acceleration rates for "send to..." commands and SMS moves