Revert "[#960336] Add Audiour url support."

This reverts commit 7ff7fbf7a0a23e5925512e2a38631fef05e33b1c.
v2.0.52
Bug 904165 - Fix image uploader replacing thumbnail image
Fix Bug 964314 - Prevent failed soundcloud searches from crashing the server
2.0.53
[#963170] Removed json editor dialog from tracks.
[#964308] Better error handling instead of timeouts. If no error event is returned, we still timeout.
v2.0.54
[bug 961155] - Bug Fixed; nav.css file packaged with bower.

Close gh-438.
Bug 964957 - Fix embeds to work with OPTIMIZE_JS = false