Update submodule sitl_gazebo to latest Tue Oct 16 14:40:21 EDT 2018

    - sitl_gazebo in PX4/Firmware (304e00f1): https://github.com/PX4/sitl_gazebo/commit/d1f0bd4367d1cab01c772bb593a3f750b2f7dce2
    - sitl_gazebo current upstream: https://github.com/PX4/sitl_gazebo/commit/3d80f63562c24c1537e1f8423ce649c99ebc15ea
    - Changes: https://github.com/PX4/sitl_gazebo/compare/d1f0bd4367d1cab01c772bb593a3f750b2f7dce2...3d80f63562c24c1537e1f8423ce649c99ebc15ea

    3d80f63 2018-10-16 Elia Tarasov - add missing dimension
4722a06 2018-10-15 Elia Tarasov - fix px4flow gyro orientation wrt camera
7e22adc 2018-10-15 Elia Tarasov - fix px4flow gyro sensor handling:
30337e7 2018-10-15 Elia Tarasov - add px4flow gyro sensor to px4flow jinja model
dcf2c95 2018-10-12 Elia Tarasov - add px4flow gyro sensor handling
0b4d4e3 2018-10-12 Elia Tarasov - replace integrated onboard gyro calculation by px4flow gyro sensor
df516e6 2018-10-11 Elia Tarasov - add check for NAN in case of no gyro is present
bbe2d67 2018-10-11 Elia Tarasov - send NAN in case of gyro absence
354e055 2018-10-11 Elia Tarasov - add default flag for gyro presence

sitl_gazebo @ 3d80f635

-Subproject commit d1f0bd4367d1cab01c772bb593a3f750b2f7dce2
+Subproject commit 3d80f63562c24c1537e1f8423ce649c99ebc15ea