PWM polarity is sometimes inverted. #37

From @cautiousCentaur on April 17, 2016 1:53

I have this error when initializing an object method that calls analogWrite. It causes my logic to be inverted so that 1 means off, and 0 means on. It only happens sometimes, so I can't simply change the logic.

self.Dim = function(amount){
bone.analogWrite(self.pin, (amount));
self.state = amount;
}
self.Dim(0.0);

Sunset_dim = new GrowSwitch("P8_13",1,true);
error: Error enabling PWM controls: Error: ENOENT, no such file or directory '/sys/devices/ocp.3/bs_pwm_test_P8_13.21/polarity'
info: Error enabling PWM controls: Error: ENOENT, no such file or directory '/sys/devices/ocp.3/bs_pwm_test_P8_13.21/polarity'
error: error updating PWM freq and value: /sys/devices/ocp.3/bs_pwm_test_P8_13.21, Error: ENOENT, no such file or directory '/sys/devices/ocp.3/bs_pwm_test_P8_13.21/duty'
{ pin: 'P8_13',
active: 1,
isPWM: true,
state: 0,
Dim: [Function] }

Copied from original issue: jadonk#122