Creating lockfiles for filters

Created by: siranipour

Ok sorry for the premature PR, but I'm really at my wits end regarding how to implement this. The example in reportengine.configparser confuses me more than it helps because parse_filter_defaults already exists in config.py

I'm fairly sure the decorator as it is in a40ed64 is incorrect, but following the docstring, this is where it suggests to place it.