Add filter to allow canceling loading of Oxygen

[benfavre]

I don't need oxygen to run on my Rest API endpoints. You do work too early in the plugin so even if I deregister the plugin in the "option_active_plugins" your stuff is allready loaded. I have added a filter to your root "functions.php" file.

$shouldLoad = apply_filters('load_oxygen', true);
if (!$shouldLoad) {
    return;
}

Please consider adding it to next release, thanks.

[KarzanTT]

+!

[wala0003]

+1