add unit tests (serialized) (issue #7)

This version introduces multiple enhancements:

allow to test object creation with serialized data

Details of additions/deletions below:
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Modified:   Test/ObjectTest.php
            -- Added --
                testCreationWithSerializedArray allow to create object with given serialized array
                testCreationWithSerializedObject allow to create object with given serialized object (only empty method)
                usage of Zend\Serializer\Serializer
            -- Updated --
                _exampleSerializedData return serialized string or serialized object
                testDataValidation fixed test assertion