Fix: Host already had the port attached

This happened when providing a port number in the URI as the `Host`
field still has the port number while the `Hostname()` method only
returns the hostname without the port.

fixes #33

Signed-off-by: Knut Ahlers <knut@ahlers.me>

auth_ldap.go

@@ -262,7 +262,7 @@ func (a authLDAP) dial() (*ldap.Conn, error) {
 		return nil, err
 	}
 
-	host := u.Host
+	host := u.Hostname()
 	port := u.Port()
 
 	var l *ldap.Conn