Save full path of workflow file in workflow object.
Added Reporter and FileReporter to perform reporting using JSON.

The FileReporter knows where to move the log file when it is finalized.
Reporter doesn't need to know about workflow id.
Introduce reporting as part of environment.
Merge branch 'feature/reporting' into develop

Conflicts:
	gwf/__init__.py
	gwf/environment.py
	gwf/task_scheduler.py
	gwf/workflow.py