Change observer to be pole placed gain matrices.

Also, Kalman filter measurement noise covariance matrix was being scaled by
0.01, so the resulting gains were trusting measurements way too much. This
explains the noisy estimator response that we observed in 001.dat of 03JUL2013.
Change the gyro y axis sensitivity back to manufacturer specification.

All runs on 04JUL2013 used the firmware from this commit.  We did 13 runs
(000-012), with the last run crashing at 5.0 m/s.