(Issue #3780) Restrict upload new version to a single file
(Issue #3780) add error messages when uploading not possible
(Issue #3780) consolidate error messages
Merge pull request #3780 from sathomas/issue3780

Upload new versions shouldn't allow multiple files to be selected (e.g. by dragging and dropping a folder)
Merge branch 'oaemaster' into avocet-master-merge
Added back qunit tests