Allow selection for user name in policies

[ra-at-diladele-com]

Type a u an there should be a drop box with all users starting with u. Should lookup users in local user database/ldap/etc.

Original request

 * I'm creating a new User: Squid -> Local User Authentication
* Creating a list of users: parents, kids, guests, etc...
* Activate: Activate Local User Database proxy authenticator.

Now I want to add these users to Webfilter Policies:

* I would like to expect my created users to select: