only tested in simulation

articulated object writer: implementation such that the default behavior is changed: by default, only the instance will be stored and not the class

ArticulatedObjectWriter: adding alternative implementation for storeArticulatedObject which should be more efficient

fixing race conditions: lock_guard was not assigned to a variable and thus optimized out by the compiler

armem_system_state/server/LightweightSystemMonitor/linux_systemutil: fixing includes (adding missing header; moving iostream to cpp)