spec_helper: set DEFAULT_DATABASE_PORT to 1521
spec_helper: set DEFAULT_DATABASE_PORT to 1521

Having undefined DEFAULT_DATABASE_PORT env variable resulted in port 0
instead of 1521. This change is resolving that.

yahonda/ruby-plsql,rsim/ruby-plsql,yahonda/ruby-plsql,rsim/ruby-plsql,JDominator/ruby-plsql,jgebal/ruby-plsql,JDominator/ruby-plsql,jgebal/ruby-plsql,jgebal/ruby-plsql