appdb: makeSafe improvement

[Vitaly Lipatov]

After last security fixes in AppDB there is introduced makeSafe function with 
one parameter.

Typical using of makeSafe:
$aClean['sub'] = makeSafe($_REQUEST['sub']);

When $_REQUEST does not contain 'sub', we get "Notice: Undefined index:" if 
mod_php in strict mode (do not permit undefined variables).

What about use makeSafe in the form
$aClean['sub'] = makeSafe($_REQUEST,'sub');
Then we can use isset inside makeSafe for additional checking.