Fix image tags in public/default.html to use asset pipeline

public/default.html

@@ -91,7 +91,7 @@
       <div id="contentr">
         <div id="header" style="margin-bottom:24px;">
           <a id="login-link" href="login">Log In</a>
-          <img src='images/logo_caps.png'/>
+          <img src='assets/logo_caps.png'/>
         </div>
 
         <div id="about" style='display:none;'>
@@ -111,19 +111,19 @@
           <ol id="steps">
             <li>
               <h2>Configure your <abbr class="helpful" title="A Diaspora installation">pod</abbr></h2>
-              <img src='images/icons/cog.png'/>
+              <img src='assets/icons/cog.png'/>
               <p>Look at <code class="helpful" title='General pod configuration (location to upload photos, SSL certs, etc.)'>config/application.yml.example</code> and <code class="helpful" title="mySQL username/password">config/database.yml.example</code> for help.</p>
             </li>
 
             <li>
               <h2>Try it out</h2>
-              <img src='images/icons/smiley_laughing.png'/>
+              <img src='assets/icons/smiley_laughing.png'/>
               <p>Start by <a href="users/sign_up">creating an account</a>.</p>
             </li>
 
             <li>
               <h2>Make a contribution!</h2>
-              <img src='images/icons/pen_write.png'/>
+              <img src='assets/icons/pen_write.png'/>
               <p>Make Diaspora even better!  Fork the project on <a href="http://github.com/diaspora/diaspora/" title="github">github</a>, make some changes, and submit a pull request.</p>
             </li>
           </ol>