Add test for db merge

1) make token name a constructor parameter and remove all other implementations of this method
2) I've created builders for domain objects (i.e. DataMap, Db\Obj Entity, Db\Obj Attribute, ...) and Factory for all builders; Main goal to provide easy way of construction objects and fill them partially with only data that necessary for test case, everything else required to make object valid will be generated randomly.
3) DbMergerTest - test correct identification of DbToModel changes
4) TokensReversTest - test compliance with the invariant token.reverse.reverse == token
5) TokensToModelExecution - test application correctness of DbToModel tokens
6) new dependency datafactory - in order to use random data in tests where exact value not really important