Implement separately events of contents updating and attributes changing

[atercattus]

For example in Inotify.queue_events():
elif event.is_attrib:
klass = ACTION_EVENT_MAP[(event.is_directory,
EVENT_TYPE_MODIFIED)]
self.queue_event(klass(event.src_path))

In tasks of files synchronization it is necessary to check the file's size and hash when attributes were simply changed.

Can add new ACTION_EVENT_MAP items like as "(True, EVENT_TYPE_ATTRS) : AttrModifiedEvent" or FileSystemEvent.is_attr_changed property?

I apologize for my bad English.

[BoboTiG]

Let's move the discussion to #260.