Fixed problem opening host adder dialog.

The hidden fqdn field in the host adder dialog has been changed to
use a generic widget instead of text widget to avoid null pointer
error since the UI elements are never created.

Ticket #1788

install/ui/host.js

@@ -121,6 +121,7 @@ IPA.entity_factories.host = function () {
             height: 250,
             fields: [
                 {
+                    factory: IPA.widget,
                     name: 'fqdn',
                     optional: true,
                     hidden: true