updated README
add getPathArray and getAttr method to get/set qualified path
add code to get qualified path value
refactored code to get benefit of minification process
add bubbleEvent function to avoid large clouser to handle `all` proxy call
added code to get index of model in collection whose child has been changed
and related test cases
refactored code for `clone` method by using `toJSON` and `constructor`;
Changed to class relationship diagram and updated examples for v0.3.1 fix