Do not load apps when an upgrade is due

This makes it still possible to update from the command line, but
disables custom commands from apps
Merge pull request #9861 from owncloud/console-dontloadappsonupdate

Do not load apps in console.php when an upgrade is due
fix sharing update, add proper escaping
[tx-robot] updated from transifex
Merge pull request #9867 from owncloud/fix_sharing_update

fix sharing update, add proper escaping
Extend OC_Util::needUpgrade to also catch app upgrades
Throw an exception when we try to load an app that needs to be upgraded
handle service not available exceptions in index, remote and public.php
extract upgrade parts to their own methods
Allow loading app without checking the upgrade
Send feedback from upgrading apps to the upgrade ui
Also set the app version when updating from app store
Set maintaince mode when updating an app from the app store