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

This version introduces multiple enhancements:

added some alias function and fixes

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

Modified:   Data/Collection.php
            -- Added --
                get alias for getElement method
                change alias for changeElement method
            -- Updated --
                _prepareCollection fixed data preparation when data is null
                delete logic moved into removeElement
                removeElement added logic responsible for removing element from collection

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