views: fixup regressions in new dmail, new feedback forms.

Fixup regression in 59b277ead. Simpleform expected `to_name`,
`user_name` methods to exist on these models.

app/views/dmails/_form.html.erb

@@ -1,5 +1,5 @@
 <%= simple_form_for(dmail) do |f| %>
-  <%= f.input :to_name, :label => "To", :input_html => { data: { autocomplete: "user" } } %>
+  <%= f.input :to_name, :label => "To", :input_html => { value: dmail.to.try(:name), data: { autocomplete: "user" } } %>
   <%= f.input :title, :as => :string %>
   <%= dtext_field "dmail", "body" %>
   <%= f.button :submit, "Send", :data => { :disable_with => "Sending..." } %>