Media library should not show edit or delete links for non-admins

[mrmist]

When viewing the media library non-admins/editors are given "edit" and "delete" links next to media content owned by other users.

Clicking delete gives a wp_die that they cannot delete the post.
Clicking edit goes back to the dashboard.

Neither edit nor delete links should be shown for non-admin/editors for content that does not belong to them. (In fact it's a toss-up if the other user content should appear at all, given that there's a multi-item delete action available that then behaves akwardly.)

9570 via svn.

[ryan]

(In [9686]) Check caps when showing media edit and delete links. fixes #8117