Anonymous Questionnaires export users' departments in results

Expected behavior: All user-related data should be stripped out when displaying or exporting results.
Actual behavior: Certain pieces of user-related data are exported, such a department.

To reproduce:

1. Create a Questionnaire. Set the respondent type to "anonymous."
2. Have some users respond. (These users must have a department set in their user profile; otherwise, the department column will be blank in the export.)
3. Export the results as a CSV file. Note that there is a "department" column, and that it contains the users' departments.