Extract Firebird / Sqlserver / Oracle database tasks, and They should be deprecated.

We'll introduce new `database_tasks.rb` and register tasks api since rails 4.0.

Thus, I think we should extract and deprecate `firebird` / `sqlserver` / `oracle` database tasks because they should be supported by 3rd-party adapters.

/cc @rafaelfranca @carlosantoniodasilva @yahonda