The new admin page broke the updating of the max upload size. This is
due to very old code there.
* Now update is done in the background using js
* Added proper route+controller to update
Fixes#994
- Also fixes a few JSHint warnings in files app
- Added "global" comment on top of files app to suppress warning and
also inform devs about what globals are use
Roeland Jago Douma
Morris Jobke
Jan-Christoph Borchardt
Vincent Petry
Georg Ehrke