Caption editing in attachment MCE views

[koopersmith]

For attachments in TinyMCE, we should be able to both toggle and edit captions. This will be similar to the process used in #21807.

[nacin]

Removing views and restoring 3.4 behavior, see #21813 (comment 30), should resolve this for 3.5.

[koopersmith]

In 22567:

Media: Restore 3.4 editor behavior and remove TinyMCE views.

• Reactivates the wpgallery and wpeditimage TinyMCE plugins. Deactivates the wpviews TinyMCE plugin.
• Moves still-relevant logic from mce-views.js to media-upload.js and shortcode.js.
• No longer include wp-includes/js/mce-views.js. This code will not be used in 3.5, and should be considered unstable.
• Currently, this is the real 3.4 experience; as such, editing triggers the old modals. Changing this is the next major step.

When reassessing views, we should look over all of these tickets and anticipate these bugs accordingly.

fixes #21813, #22123, #22155, #22161, #22257, #22266, #22318, #22407, see #21390.