Use $rootPkg instead of "gnorm"

[freb]

I believe there are two function signatures that should be updated from gnorm.db to {{$rootPkg}}.DB:

• https://github.com/gnormal/postgres-go/blob/master/gnorm_templates/table.gotmpl#L281
• https://github.com/gnormal/postgres-go/blob/master/gnorm_templates/table.gotmpl#L70