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

This version introduces multiple enhancements:

added some logic about pages and modified some methods

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

Modified:   Data/Collection.php
            -- Added --
                loopPages set loop on collection to iterate on pages, if false on elements
                _getPage return elements for page with given index
                $_loopByPages if true loop on collection will iterate on pages, otherwise on elements
                isLoopByPagesEnabled return information witch loop is used for collection
            -- Updated --
                getPreviousPage added method logic
                getNextPage added method logic
                getPage added method logic
                getLastPage added method logic
                getFirstPage added method logic
                last removed checking that data should be changed
                first removed checking that data should be changed
                getElement removed checking that data should be changed
                _isPageAllowed fixed checking page for page 1
                getFullCollection removed checking that data should be changed
                _prepareCollection added checking that data should be changed
                serialize removed checking that data should be changed

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