Frame_params: 3DR_X8+_RTF.param

Adding param file for 3DR X8+
GPS: use primary for Notification
GPS: init primary_instance to zero
AP_AHRS : Add reset of EKF gyro bias states
AP_NavEKF : Add public method to reset gyro bias states
Copter: fail to arm if gyro cal fails
Copter: re-enable CPU failsafe if arming fails
AP_NavEKF : add INIT_GYRO_BIAS_UNCERTAINTY definition
Copter: update AC3.2-rc14 ReleaseNotes
PX4: conditionally build auth command and libraries

this makes it possible to build with upstream master
PX4: add TESTS_MATHLIB_DISABLE define

this helps building with upstream master
PX4: fixed startup log msg location
autotest: added developer build support

this creates firmware builds for developers in the devbuild directory
autotest: added link to devbuild tree
AP_HAL_Linux: [Bugfix] prevent memory acces violation in process_dsm_pulse

When a S.Bus signal is fed into the rcin-Pin AruPlane on the BBB get's a
Segmentation fault. This patch prevents the memory acces to dsm_state.bytes[16] outside
of the array bounds. The patch should be reviewed by sombody who knows the DSM protocol,
as i don't.
scripts: fixed devrelease permissions
HAL_Linux: add PCA9685 based RCOutput for Navio
HAL_Linux: add GPIO driver for Raspberry Pi
HAL_Linux: Initialize i2c before rcoutput (required by i2c pwm chips for initialization)
HAL_Linux: separate RCInput for PRU and Navio