Logging token path over a process

Hi @mattmclaren @caleeli, 

I want to track token path over a process, using a TXT file, please could you point me to an easy solution?

In addition, could you show me how this line [ParallelGateway.bpmn#L18](https://github.com/ProcessMaker/nayra/blob/master/tests/Feature/Engine/files/ParallelGateway.bpmn#L18) with `CREATE_LOG_FILE` is processed by the engine? 
