Feature/add people tool

This includes changes for displaying member count for each section, on the page that displays the list of sections. The UI has also been modified to reflect the count.(As of now all the enrollees will be displayed. If there are people having 2 roles within a section, they will be counted separately. If it's determined that this needs to change, additional filters could be applied, but the  base method would still remain the same)
We discussed this approach, but there is an issue with the 'last' link, I think. The way I read it, Canvas doesn't guarantee that the 'last' link will be there -- even for requests that return more than one page's worth of results -- if it deems that getting 'last' would be too expensive of an operation. https://canvas.instructure.com/doc/api/file.pagination.html