Better handling for access issues

[nathanperkins]

Issue
When logged in as a restricted user, trying to open some restricted pages will give a generic error or Internal Server Error (500). Messaging could be improved by returning a page that states the current user is in a group that does not have access to the resource.

How to replicate

1. Attempt to login as a user that has no access.
   or
2. Create a support user in the ACLs and login as that user.
3. Attempt to access the ACL page.

[nathanperkins]

Sometimes, I see an access denied message, so it's not consistent.

For an example, I'm logged in as a user that no longer has access and I'm getting an internal server error (500), with no option to logout. I have to clear my browser cookies to get back in.