add unit tests, some fixes (issue #7)

This version introduces multiple enhancements:

finished all basic tests for BlueObject
fixed some issues in BlueObjects founded during test writing

Details of additions/deletions below:
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Modified:   Base/BlueObject.php
            -- Updated --
                serialize removed unused parameter from traveler method call
                compareData refactored switch statement
                _comparator fixed comparison operators
                traveler fixed changing data in object by reference usage

Modified:   Test/ObjectTest.php
            -- Added --
                testObjectMerging test object merging
                testDataTraveling test method to walk on all elements in object and call on them given function
                testObjectComparison test comparison of whole objects
                testDataComparison test comparison of some data in object