Add the ability to choose the column used to search for periodic scopes.

Signed-off-by: James McCarthy <james@thisishatch.co.uk>
Ensure period scope is not added to the scopes when add_period_scopes_to_base_relation is false.

Signed-off-by: James McCarthy <james@thisishatch.co.uk>
Rename add_period_scopes_to_base_relation to add_period_scopes_to_base_relation?

Signed-off-by: James McCarthy <james@thisishatch.co.uk>