Move editing the vote description to a dedicated page

So that /votes/:id remains a preview page, even for organizers.

views/votes_edit_description.erb

@@ -0,0 +1,13 @@
+<h1><%= _("Edit vote description") %></h1>
+
+<form action="/votes/<%= @vote.secure_id %>/edit" method="post">
+  <p>
+    <label for="title"><%= _("Title") %></label>
+    <input type="text" name="title" value="<%= @vote.title %>">
+  </p>
+  <p>
+    <label for="description"><%= _("Description") %></label>
+    <textarea type="text" name="description"><%= @vote.description %></textarea>
+  </p>
+  <button type="submit"><%= _("Save") %></button>
+</form>