Fix Segfault caused by std::bad_alloc in RobotUnitModuleLogging
Related to #120
Adds two properties:
- One for the maximum size of the backlog (as it seems to accumulate memory even though it has a maximum retention time)
- One for disabling the backlog altogether, as the memory leak is unrelated to the segfaults on ARMAR-DE
This has been tested on ARMAR-DE for >20min