Use built-in form sumbit translation keys for diary comments

Also use a diary comment object as the basis for the form

app/views/diary_entries/show.html.erb

@@ -19,9 +19,9 @@
 
     <%= error_messages_for "diary_comment" %>
 
-    <%= form_for :diary_comment, :url => { :action => "comment" } do |f| %>
+    <%= form_for @entry.comments.new, :url => { :action => "comment" } do |f| %>
       <%= richtext_area :diary_comment, :body, :cols => 80, :rows => 15 %>
-      <%= submit_tag t(".save_button") %>
+      <%= f.submit %>
     <% end %>
     <% if @entry.subscribers.exists?(current_user.id) %>
       <div class="diary-subscribe-buttons"><%= link_to t("javascripts.changesets.show.unsubscribe"), diary_entry_unsubscribe_path(:display_name => @entry.user.display_name, :id => @entry.id), :method => :post, :class => :button %></div>

config/locales/en.yml

@@ -7,6 +7,8 @@ en:
       blog: "%e %B %Y"
   helpers:
     submit:
+      diary_comment:
+        create: Save
       diary_entry:
         create: "Publish"
         update: "Update"
@@ -324,7 +326,6 @@ en:
       leave_a_comment: "Leave a comment"
       login_to_leave_a_comment: "%{login_link} to leave a comment"
       login: "Login"
-      save_button: "Save"
     no_such_entry:
       title: "No such diary entry"
       heading: "No entry with the id: %{id}"