title: Git signed-off-by custom format
body: <p>Is there any possibility to change default format of <code>Signed-off-by</code> line.</p>
  
  <p>By default is:</p>
  
  <pre><code>Signed-off-by: user.name &lt;user.email&gt;
  </code></pre>
  
  <p>Some of project require another format, eg:</p>
  
  <pre><code>Signed-off-by: user.name &lt;user.email&gt; (github: account_name)
  </code></pre>