Update to Backbone 1.0.0

[mattwiebe]

Backbone 1.0.0 was released today.

I've done a cursory test of the media modal and the current state of revisions and everything appears to be working fine.

[koopersmith]

That's not the case — Collections were changed to fire "set" instead of "reset", which is causing a bunch of breakage. The patch doesn't bust the cache, so you were likely still seeing 0.9.10.

[koopersmith]

This should get us most of the way there. I think there still may be a rough edge or two; please test and record what you find.

[nacin]

In 23893:

Backbone 1.0.0.

Update media JS to reflect changes. Please open new tickets for remaining issues.

props koopersmith.
fixes #23830.

[kovshenin]

I tried to debug this, but seems like it's beyond my backbone skills. After the 1.0.0 update in [23893], the Attachments collection has always got one more element than it should, resulting in an weird empty element on all media screens: ​http://cl.ly/image/3x033D2i0H3t

[SergeyBiryukov]

Replying to kovshenin:

After the 1.0.0 update in [23893], the Attachments collection has always got one more element than it should, resulting in an weird empty element on all media screens: ​http://cl.ly/image/3x033D2i0H3t

Let's handle this in #24094.

[markjaquith]

In 24771:

Fix a media regression in [24110] that could cause duplicate models.

Props garyc40. Fixes #24753. See #24094, #23830.