Converted the Membership rate form to an Ajax remote form.

* Changed the form_for to be a remote_form_for
* Changed the url to use the js format
* Added RJS to add the Saved rate to the rate cell
* Added id to the table cell so the rate cell can be replaced on success
* Added an Error RJS to flash an error message

  #1921

app/views/rates/create.js.rjs

@@ -0,0 +1,2 @@
+element = 'rate_' + @rate.project_id.to_s
+page.replace_html element, "<strong>#{link_to number_to_currency(@rate.amount), { :action => 'edit', :id => @rate.user, :tab => 'rates'} }</strong>"

app/views/rates/create_error.js.rjs

@@ -0,0 +1,5 @@
+content = render_flash_messages
+page.select("div.flash").each do |value, index|
+  page.hide value
+end
+page.insert_html :top, 'content', content

app/views/users/_memberships.rhtml

@@ -23,7 +23,7 @@
       <%= link_to l(:button_delete), {:action => 'destroy_membership', :id => @user, :membership_id => membership }, :method => :post, :class => 'icon icon-del' %>
     </td>
     <%# TODO: Hook %>
-    <td>
+    <td id="rate_<%= membership.project.id %>">
       <% rate = Rate.for(@user, membership.project) %>
 
       <% if rate.default? || rate.nil? %>
@@ -31,7 +31,7 @@
         <em><%= number_to_currency(rate.amount) %></em>
         <% end %>
 
-        <% form_for(:rate, :url => rates_path) do |f| %>
+        <% remote_form_for(:rate, :url => formatted_rates_path('js')) do |f| %>
 
         <%= f.text_field :amount %>
         <%= f.hidden_field :date_in_effect, :value => Date.today.to_s %>