Load apps proper master

@karlitschek @icewind1991 @blizzz 

Basically all apps of type filesystem, authentication and logging are loaded now in OC:init().
This should bring up the very basic essential minimum.

Within handleRequest() all apps are loaded.

Following entrypoints need further analysis to find out if this basic minimum is enough:
- [x] ocs/v1.php - Looks like we need to load all apps because any app can register ocs routes
- [ ] public.php - e.g. file_sharing still loads all apps manually because of previews 
- [ ] remote.php - e.g. this is e.g. used for webdav - no further apps are required