[icubmod] Added documentation for parameters used by CanBusAnalogSensor
[icubmod] add missing check in required physDevice parameters in CanBusAnalogSensor
[icubmod] Corrected documentation of canDeviceNum parameter
fix travis by installing cmake 2.8.11
Merge branch 'canbusDocs' of https://github.com/traversaro/icub-main into canbusDocs

Conflicts:
	.travis.yml
[canBusAnalogSensor] add group doxygen documentation
Update CanBusAnalogSensor.h
Merge pull request #49 from traversaro/canbusDocs

Added documentation for parameters used by CanBusAnalogServer