Add :if_update option in order to allow counter to be conditionally incremented/decremented when an update has been made to an embedded/referenced object.
Updated specs for :if_update option.
Bump version to 1.1.1. Updated CHANGELOG and README.
Add new spec classes.
Merge pull request #15 from joe1chen/add_if_update_option

Add if_update option for conditionally updating counter in after_update hook.