create Collection class (issue #4)
create Collection class (issue #4)

This version introduces multiple enhancements:

fixed data preparation before retrieve
added method to handle data retrieve callbacks

Details of additions/deletions below:
--------------------------------------------------------------

Modified:   Data/Collection.php
            -- Added --
                putRetrieveCallback add data preparation rules before add data into collection
                returnRetrieveRules return all current preparation rules
                removeRetrieveRules remove given preparation rule name or all rules
            -- Updated --
                _prepareCollection fixed data preparation before return
                stopInputPreparation added correct logic
                startInputPreparation added correct logic
                stopOutputPreparation added correct logic
                startOutputPreparation added correct logic

bluetree-service/data,bluetree-service/collection,chajr/class-kernel,chajr/class-kernel,bluetree-service/container