Data preparation in __constructor (issue #48)

This version introduces multiple enhancements:

allow to launch data preparation in constructor
applied for XML, JSON, stdClass, serialized and array
also some documentation update

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

Modified:   Base/BlueObject.php
            -- Updated --
                __call documntation update
                returnOriginalData documntation update
                compareData documntation update
                _appendJson apply data by setData method
                _appendSimpleXml apply data by setData method
                _appendXml apply data by setData method
                _appendArray apply data by setData method
                _appendStdClass apply data by setData method
                _appendSerialized apply data by setData method

Modified:   composer.json
            -- Modified --
                changed version from 0.2.7 to 0.2.8