title: Update Moodle to the newest secure version
body: <p>I bacame from my colleague an old but very custome <code>Moodle 2.7.3</code> version, which wasn't updated until now. Even the <code>security updates weren't made</code>. 
  Because the version is highly customize, it <strong>won't be possible</strong> to just copy-paste the code and make it to the newest <code>2.7.x stable version</code>. 
  Should I begin to compare it as follows:</p>
  
  <ul>
  <li>2.7.3 VS 2.7.4 (adjust the newest code)</li>
  <li>2.7.4 VS 2.7.5 (adjust the newest code)</li>
  <li>... (adjust the newest code)</li>
  <li>2.7.14 VS 2.7.15 (adjust the newest code)</li>
  </ul>
  
  <p>And by each compare to adjust the newest code with the code snippets, without changing version in the means of standard update?</p>