update authentication system to Devise

app/views/charts/_display.html.erb

@@ -2,10 +2,10 @@
 
   <iframe id="iframe<%= index %>" width="<%= width %>" height="<%= height %>" style="border: 1px solid #cccccc;" src="" default_src="<%= src %>"></iframe>
 
-  <br /><br />
+  <br><br>
 
   <%= t(:chart_embed_code) %>:
-  <br />
+  <br>
   <textarea id="embed<%= index %>" rows="5" cols="53">&lt;iframe width="<%= width %>" height="<%= height %>" style="border: 1px solid #cccccc;" src="<%= src %>">&lt;/iframe></textarea>
 
-<br /><br /><br />
+<br><br><br>

app/views/charts/index.html.erb

@@ -46,9 +46,9 @@
       <div class="helplink">(<a href="/docs/charts"><%= t(:help_options) %></a>)</div>
       <h2><%= t(:help_charts) %></h2>
       <%= t(:help_charts_options) %>
-      <br /><br />
+      <br><br>
       <%= t(:help_charts_embed) %>
-      <br /><br />
+      <br><br>
       &bull; <a href="http://community.thingspeak.com/tutorials/wordpress/how-to-embed-a-thingspeak-chart-on-your-wordpress-blog/">WordPress Tutorial</a>
     </li>
   </ul>