[bitshares/bitshares-core] remove not needed budget_record_object creation from maint (#1213)

removed budget_record_object completely as suggested at https://github.com/bitshares/bitshares-core/pull/1213#pullrequestreview-145925723

cant remove `budget_record_object.hpp` as the `budget_record` struct is needed.

we can maybe change the name of that file to just `budget_record.hpp` or move the struct somewhere else.