title: Add condition to gulp building process based on html attribute
body: <p>Is it possible to add a condition such that every <code>img</code> tag in all html files inside my project should have another attribute like <code>my-custom-directive</code>?</p>
  
  <p>I have an angular directive which modifies the base URL of a relative img src URL inside my webapp and I want to prevent me team members from missing this attribute in the html template they write.</p>