Project view: tolerate non-existing users

Show user as deleted if it is suddenly not found.

Change-Id: I4bd4d511a5e22da6de34f56f86eff178b3fb5f47
Empty project user list when LDAP integration is on

Before this change, user list in project view might return
Internal Server Error status because NotFound were raised
while rendering the template.

Change-Id: I0a421ed7f6b631e1ca21169c514b0e2b82adb39f
Updated LDAP/AD management forms

- unified style;
- removed misleading help text;
- added cancel button.

Change-Id: I7a4554085c0b02909a4bc2b4c3c0b4d589529933
Sort choices in ad project membership form

It's really hard to find object in long unsorted list.

Change-Id: I28be28146e902678588d49ece685197eb8d1acb5
Better auth behavior if user is deleted while logged in

Change-Id: I9ee5a1aa06c5b8b325ed6f3dcf2b4af07716ac73
Fix redirect loop on PermissionDenied

When user looses permission for the page he is looking at, referrer
might be the same page or also unaccessible, which leads to redirect
loop.

This commit deals with such behavior by redirecting to dashboard in
cases of permission errors.

Change-Id: Ia58ce5e801d527826a5fd03e3830623bd7293b90