Do not grant superuser rights to the dbo user anymore (#402)

* Do not grant superuser rights to the dbo user anymore

* Add 'createrole' permission to dbo

Author: eberlep

api/v1/postgres_types.go

@@ -546,7 +546,7 @@ func (p *Postgres) ToUnstructuredZalandoPostgresql(z *zalando.Postgresql, c *cor
 
 	// Create database owner
 	z.Spec.Users = make(map[string]zalando.UserFlags)
-	z.Spec.Users[ownerName] = zalando.UserFlags{"superuser", "createdb"}
+	z.Spec.Users[ownerName] = zalando.UserFlags{"createdb", "createrole"}
 
 	// Create default database
 	z.Spec.Databases = make(map[string]string)