Adds hook to context.from_path

This hook allows developers to add onto the context.from_path method to perform any custom logic necessary.

Our current use case is we are associating Tasks with workfiles.  While Toolkit currently doesn't support this officially, we have developed a data model that allows for us to do this using custom logic.  This hook allows us to add the Task to the context when resolving a path that points to a workfile.

Please let me know if you have any additional questons!  (Also there are a bunch of whitespace changes, I apologize for that).