Adding support for configurable order of result in generators #25

[phochste]

Adding support to choose at Store or Bag level how default ordering of generators should work:

store:
    mydb:
         package: DBI
         options:
            data_source: "dbi:mysql:database=mydb"
            username: xyz
            password: xyz
            default_order: NONE
            bags:
                foobar:
                   default_order: ID

Options are:

• NONE - don't order
• ID - order on the standard set ID field
• $field - order on a $field column name