[imp] image blocking in inline html messages searches all turba sources

[liamr at umich.edu]

We're running the beta stuff on our development webmail server, I've turned on
inline HTML viewing w/ the "block stuff that's not from someone in your
addressbook" option.  Viewing HTML messages is *really* slow.  Looking at the
horde logs, it searching both the user's individual addressbook and out LDAP
server.  The only "search_source" that's defined is the SQL database.  Should
it be querying all the sources that are defined in Turba?

Liam