Add option to config esc

This way we can calibrate PPM range and
also configure battery type and enable/disable brake.

REMEMBER: most of ESC enter in configuration mode when
the first PPM pulse is in the maximum value. This way
motors will not arm and start spinning.

Look at your esc documentation to know how proced configuration.
Remove unnecessary function motors_velocity_get()
Setup all motors to portB pins
Add DCM Mahony motion algorithm just in case madgwick had a poor accuracy on air
Fix missing character in radio message
Update motors_velocity_set() signature in motors.h
Add flash to enable/disable write in flash

Until we are developing dont write to flash.
temp