Wrote a global documentation for the control system manager.
Changed control system manager's README.

Added a part about changing consigns and adding ramps to the control
system manager tutorial.
Added a README for the PID filter.

I added a readme and some pictures about how the PID filter is
implemented in the system.
Added some doc for the commandline module.
Added a README.md file for the uptime module.
Added some docs for robot_system.
Merge pull request #24 from antoinealb/master

Add some doc