Implement default PHP interfaces (issue #27)

This version introduces multiple enhancements:

added some dafault interfaces to Object class and methods to handle that interfaces into BlueObject
examples

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

Added:      examples/base_object/array_access.php
            -- Added --
                example of usage object as array

Modified:   examples/base_object.php
            -- Added --
                example of usage object as array

Modified:   Data/Object.php
            -- Added --
                Serializable, ArrayAccess and Iterator interfaces

Modified:   Base/BlueObject.php
            -- Added --
                $_integerKeysCounter for array access numeric keys, store last used numeric index
                unserialize to handle `Serialize` interface, clear `_DATA` array and lunch constructor to set up data