UI fixes

[cecilialau6776]

• Notifications badge on project detail page now only counts the number of notifications the user can see
• Allocation change request page's approve, deny, and update buttons now have consistent spacing
• Only users can edit a change request can see the edit button on the list in the allocation detail page
  • I took the condition from test_func() in AllocationChangeDetailView - maybe it's cleaner to have a static function in that class (such as def can_view(user, allocation_obj)) to call
• Add "Request Change" button to the allocation change requests section of the allocation detail page

Closes #739.