Teach whedon to unassign editor

[danielskatz]

Sometimes, the AEiC may start a metareview for a paper where the author suggested an editor but the AEiC does not actually want to assign that editor, or at least not without checking with the editor. If the AEiC is not paying enough attention, and just starts the metareview (for example, so that they can read the generated paper and think about which editor is appropriate), the pre-review issue is created with the author-suggested editor. When this happens, it would be nice if there was a way to unassign the editor, so that they paper remains in the correct tab of the dashboard, and all AEiCs can see that there is still a need to assign an editor.