copy/save/delete is accessed via longpress for all media messages, just
like for simple text messages.
Notes
-----
We don't support saving audio attachments as it's not clear where they should go.
(I don't think users expect them to end up in their iTunes library.)
There is still no UX for "pasting" media into Signal.
Removed the now redundant (and confusing) "share" button interface.
//FREEBIE
This was done as part of unforking JSQMessagesViewController, but is
intentionally a separate commit so we can separate formatting changes
from code changes in git history.
* Import frameworks like:
#import <FrameworkName/HeaderName.h>
* instead of:
#import "HeaderName.h"
// FREEBIE
