Friday night at the question emporium

During the process of polishing my novel to query agents, I employed a professional editor. Should I include this information in my query? If so, to what extent? 

No.
No.
No.

First, leave me to my delusions that you wrote the book yourself with no help. That way I won't wonder if you can do it again.

Second, even though it's true you had help (beta readers, critique group, caustic comments from the QueryShark perhaps) I don't care how your novel came to be. I only care what it's about.

You don't have enough room in a query to add filigree.  Get the plot on the page. Tell me what the book is about. Count it as a good day's work.