Implement page caching for reports

[chiatt]

If a user is logged in as admin, reports load relatively quickly because we don't need to check nodegroup permissions. For anonymous users however, nodegroup permissions must be checked and that can have a significant impact on performance. If possible we should improve performance of checking nodegroup permissions. However, we should still implement report caching because the pages are relatively static. This would improve performance for public facing applications that might get many requests from guest users.