Use note.closed? in a consistent way

app/views/notes/_note.gpx.builder

@@ -17,7 +17,7 @@ xml.wpt("lon" => note.lon, "lat" => note.lat) do
     xml.date_created note.created_at
     xml.status note.status
 
-    if note.status == "closed"
+    if note.closed?
       xml.date_closed note.closed_at
     end
   end

app/views/notes/_note.json.jsonify

@@ -18,7 +18,7 @@ json.properties do
 
   json.date_created note.created_at
   json.status note.status
-  json.closed_at note.closed_at if note.status == "closed"
+  json.closed_at note.closed_at if note.closed?
 
   json.comments(note.comments) do |comment|
     json.date comment.created_at

app/views/notes/_note.rss.builder

@@ -1,7 +1,7 @@
 xml.item do
   location = describe_location(note.lat, note.lon, 14, locale)
 
-  if note.status == "closed"
+  if note.closed?
     xml.title t('note.rss.closed', :place => location)
   elsif note.comments.length > 1
     xml.title t('note.rss.comment', :place => location)

app/views/notes/_note.xml.builder

@@ -12,7 +12,7 @@ xml.note("lon" => note.lon, "lat" => note.lat) do
   xml.date_created note.created_at
   xml.status note.status
 
-  if note.status == "closed"
+  if note.closed?
     xml.date_closed note.closed_at
   end
 

app/views/notes/mine.html.erb

@@ -17,7 +17,7 @@
 <% @notes.each do |note| -%>
   <tr<% if note.author != @user2 %> class="creator"<% end %>>
     <td>
-      <% if note.status == "closed" %>
+      <% if note.closed? %>
         <%= image_tag("closed_note_marker.png", :alt => 'closed') %>
       <% else %>
         <%= image_tag("open_note_marker.png", :alt => 'open') %>