Scaling for gyro looks wrong

[peterhinch]

If the gyro units are degrees/s the scaling here should be 16 not 900 (datasheet section 3.6.4.3 table 3-22).

[ladyada]

thanks, wanna submit a PR? that would be great!

[peterhinch]

Now done.

[caternuson]

Looks like this was fixed by #25. Re-open if not.