change all data with getData & getData with null key (issue #26 #32)

This version introduces multiple enhancements:

fixed two bugs:
  * data preparation with `null` key will now prepare all data
  * get data will return all data even if one of key has `null` value

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

Modified:   Base/BlueObject.php
            -- Updated --
                getData with null key will always return all data
                _dataPreparation prepare data for all keys if key is null

Modified:   composer.json
            -- Modified --
                changed version from 0.2.0 to 0.2.1