Refactor FindJafar.cmake

Now we can look for Jafar modules as components passed to a
find_package(). FindJafar.cmake still need to be refactored conform
the guidelines on /usr/share/cmake-<VERSION>/Modules/readme.txt, but
I'm satisfied for now.
Add FindViam.cmake
Refactor compilation of optional modules
Correct sensor mti ros to work on online mode
Add another command to the command list file
Convert image message to MONO8 instead of BGR8.

Not tested. Doesn't know if it will work.
Some changes on Sensor Camera Ros constructors

The constructors were wrong. They were made more like the ones in
HardwareSensorCamera. I can't see the difference between the two
constructors. Looks like one is for online and other for offline
mode. Should compare with HardwareSensorCameraFirewire, but it's not
easy...
Try to use the CameraRos class

Code compiles, but is not tested yet. Should check if the calls are
correct and/or if we need to change the constructors to use it in
online mode correctly.