Merge pull request #299 from DrTon/sdlog2

sdlog2: RC (RC controls) and OUT0 (actuator 0 output) messages added
Hotfix: Excluded sdlog app from standard build, still keeping code in place for now
Add PX4Flow board modules and corresponding ORB msgs.
Merge pull request #303 from samized/flowboard_master

Add PX4Flow board modules and corresponding ORB msgs.
Log airspeed.
Increase array size.
ATSP.ThrustSP added
Report airspeed over HoTT telemetry
Fix usage help and cleanup formatting
Merge pull request #306 from sjwilks/hott-airspeed

Report airspeed via HoTT telemetry
More formatting cleanups
And yet more formatting cleanups
Merge pull request #307 from sjwilks/ets-airspeed-fix

Fix the usage help and lots of formatting fixes.
Merge pull request #305 from sjwilks/sdlog-airspeed

Add airspeed logging to sdlog2.
Fixed too low stack sizes
Merge branch 'master' into sdlog2
sdlog2 messages ID fix
Critical bug fixed, cleanup