* Merge `Composite` model with general `Attachments` model, as `Attachments.validate` and `Composite.evaluate` were functionally equivalent.
* Queries should only watch `wp.Uploader.queue`, as watching `Attachments.all` results in queries attempting to add attachments before their properties are set (which then results a few too many irrelevant adds/removes). `Attachments.all` should potentially be removed or rethought.
see #21390.
git-svn-id: http://core.svn.wordpress.org/trunk@22655 1a063a9b-81f0-0310-95a4-ce76da25c4cd