Bug 716980 - winsync uses old AD entry if new one not found
    
    https://bugzilla.redhat.com/show_bug.cgi?id=716980
    Resolves: bug 716980
    Bug Description: winsync uses old AD entry if new one not found
    Reviewed by: nhosoi (Thanks!)
    Branch: master
    Fix Description: Clear out the old raw_entry before doing the search.  This
    will leave a NULL in the raw entry.  winsync plugins will need to handle a
    NULL for the raw_entry and/or ad_entry.
    I also improved an error message.
    Platforms tested: RHEL6 x86_64
    Flag Day: no
    Doc impact: no