bug#7895: 24.0.50; `image-dired-list-tags' should use `find-file-noselect', not`find-file'

[Chong Yidong]

>> Use find-file-noselect plus `with-current-buffer' or `set-buffer'.
>
> Same thing for `image-dired-get-comment', `image-dired-remove-tag',
> `image-dired-mark-tagged-files', and `image-dired-create-gallery-lists'.
>
> IOW, _all_ occurrences of `find-file' in `image-dired.el' are
> misguided.  They should use `find-file-noselect', or in some other way
> not display the file.

Fixed; thanks for the bug report.