non-ajax Upgrade script utility, usable via CLI or wget. Requires PR 404...

...7.

Before merging, https://github.com/owncloud/core/pull/4047 must be merged. Testing will also only work when the mentioned PR is merged.

Then, upgrade.php can be run either from command line or via web browser (no fancy output, just text). Thanks to @icewind1991 for the real work with the seperation.

Reviewers? @karlitschek @Gomez @icewind1991 @dragotin