Fix division by 0 when no records match the specified filters
requested to merge 528-when-passing-per-0-as-parameter-the-page-crashes-and-an-error-is-reported into development
The issue is caused when the user has chosen to view all items on the same page, which sets the items per page to query.count (the number of returned entries), but 0 entries match the filters specified by the user (or the user does not have permission to see the results). For example: /admin/experiment_profiles?experiment_projects[round][]=123456&per=0.
This can also occur on other pages in the admin panel, for example: /admin/courses?id[]=123456&per=0.
Closes #528 (closed)
Edited by Martin Mladenov