add unit tests (other data types creation with preparation) (issue #7)

This version introduces multiple enhancements:

added test to all data types object creation with preparation
also fixed error witn incorrect accessibility of appendXml method

Details of additions/deletions below:
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Modified:   Test/ObjectTest.php
            -- Added --
                IM_CHANGED prefix for some changed data
                _dataPreparationCommon launch common object creation and assertion
                testCreationWithXmlDataPreparation allow to create object with given xml data and data preparation
                testCreationWithSimpleXmlDataPreparation allow to create object with given simple xml data and data preparation
                testCreationWithSerializedObjectDataPreparation allow to create object with given serialized object and data preparation
                testCreationWithSerializedArrayDataPreparation allow to create object with given serialized array and data preparation
                testCreationWithStdClassDataDataPreparation allow to create object with given std class and data preparation
            -- Updated --
                testDataValidation fixed test
                testCreationWithJsonDataDataPreparation whole logic moved into _dataPreparationCommon method

Modified:   Base/BlueObject.php
            -- Updated --
                appendXml changed from protected to public