mpu imu branch started
mpu files added.
progress checkin
progress-first outline of mpu9150 api
progress checkin
Added i2c error strings for debug
Downgrade i2c sck to 100khz from 400khz due to 10kohm pullups
Added mpu setup function for bypass and interrupt level
more progress
progress.
changed back to read_id
Openocd configuration file for stlink-v2 and changes to psas.mk
Merge branch 'master' into mpu
Merge branch 'master' into mpu
Updates to mpu9150_init
accel axis read x
mpu9150 reading x, y, z accel
gyro x, y, z reads
Now reading gyro (x,y,z), accel(x,y,z) and temperature(C) after
interrupt from mpu9150. Sample rate is set to 2ms.

Time to read all nine parameters at 400khz is 1.6mS. 2mS sample
rate may be too aggressive.
More progress sending MPU data over ethernet to FC.