FSEvents: can't rely on rename events coming in pairs. Check the path to...

... see if the event is old or new

If a file is moved from a directory that is not monitored to a directory that is monitored FSEvents will only report one kFSEventStreamEventFlagItemRenamed event. 

Attempted to remove the assumption made that these events come in pairs by basing it on file path existing. File path exists trigger renamed_new_name, else trigger renamed_old_name.