Send debug handler response to console.info()

No print_r(), just $resp->info([$_POST['debug'], ...])
New directives:

appcache, module-test, apache-modules, & php-modules

appcache is used for the appcache attribute

All module related directives are used for debugging, checking if all required
modules are loaded.
Debugging updates...

Fix casting $data to string in debug().

New function module_test() returns null or an array of modules
that are listed as required (see commit bc6e6ab1de3dd3bfb8262de4bc528249883a314b)
that are not loaded.
Set appcache directive if !localhost() and is set in settings.ini
Run module_test in main.php if enabled.

If test passes, continune as usual. Otherwise, list out the arrays
of missing modules.