add unit tests (issue #7)

This version introduces multiple enhancements:

added test for data preparation and validation
added test for non existing methods and updated data restoration test

Details of additions/deletions below:
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Modified:   Test/ObjectTest.php
            -- Added --
                testAccessForNonExistingMethods check that access to non existing method will create error information
                testDataValidation check set current data as original data
                testDataPreparationOnEnter allow to change data before insert for founded key using closure
                testDataPreparationOnReturn allow to change data before return for founded key using closure
            -- Updated --
                testDataRestorationForSingleData added KeyDataChanged method assertion