Update IMU_Zero.ino

[RobertRFenichel]

Added delay to keep from reading IMU faster than 200 Hz. Without the delays, program hangs on some devices. Comments expanded.

[piroozn]

@RobertRFenichel
Please do not add delay. We have to make these libraries more robust and correct by using status bits for the interface that indicate the status of the Fifo and if we need to wait or just read it.
Delay is a bad idea, Please don't use delay.

[PaulStoffregen]

Especially for gyroscope data, reading at a consistent known rate which corresponds to the actual sensor acuisition rate is essential. Converting angular rates to position involves integrating over time. Without consistent acquisition rate, you can end up with an impressively fast scrolling list of numbers that are much less useful for filters or fusion algorithms to actually do useful for computing orientation.