Do not assume existance of a "publicuser" role in CDB_UserTables

Closes #5 (take 2)

scripts-available/CDB_UserTables.sql

@@ -22,7 +22,7 @@ AS $$
       'spatial_ref_sys'
      )
   ), perms AS (
-    SELECT t, has_table_privilege('publicuser', 'public'||'.'||t, 'SELECT') as p
+    SELECT t, has_table_privilege('public', 'public'||'.'||t, 'SELECT') as p
     FROM usertables
   )
   SELECT t FROM perms