skeleton for adafruiti2cpwm driver
bring up adafruit i2c pwm driver

includes the test function, fucntionality verified with scope and servo
 adafruit i2c pwm: listen to uorb for setpoints
rename adafruiti2cpwm to pca9685
Merge pull request #1296 from PX4/adafruiti2cpwm

Adafruit i2c to pwm board driver
mavlink: missions manager compID cleanup, use the common compID, stict compID checks for incoming messages
Merge branch 'master' of https://github.com/PX4/Firmware
pca9685: correct input scaling
Merge pull request #1298 from PX4/adafruiti2cpwm

pca9685: correct input scaling
navigator: correct mode for land and termination
Merge pull request #1299 from PX4/navigatorstatefix

navigator: correct mode for land and termination
sensors: remove warnx
Merge pull request #1300 from PX4/sensorswarnx

sensors: remove warnx
Merge branch 'master' of https://github.com/PX4/Firmware
Be more permissive with mission component IDs, renamed camera to onboard link but still accepting same commandline syntax
Merge pull request #1297 from PX4/mission_fix

mavlink: missions manager compID cleanup
Merge branch 'master' of https://github.com/PX4/Firmware