Drop role management

Roles are not created anymore, previously private functions for table
information extraction (CDB_UserTables, CDB_TableIndexes, CDB_ColumnNames,
CDB_ColumnType) will now be callable by anyone while only returning
information about tables over which the calling user has SELECT privilege.

Closes #36

scripts-available/CDB_TableIndexes.sql

@@ -17,10 +17,8 @@ AS $$
   ON pg_class.oid = idx.indexrelid 
   WHERE pg_indexes.tablename = '' || $1 || ''
   AND '' || $1 || '' IN (SELECT CDB_UserTables())
-  AND pg_class.relname=pg_indexes.indexname;
+  AND pg_class.relname=pg_indexes.indexname
+  ;
 
 $$ LANGUAGE SQL;
 
--- This is a private function, so only the db owner need privileges
-REVOKE ALL ON FUNCTION CDB_TableIndexes(REGCLASS) FROM PUBLIC;
-GRANT EXECUTE ON FUNCTION CDB_TableIndexes(REGCLASS) TO ":DATABASE_USERNAME";