title: How to add new build step feature to Jenkins
body: <p>This is the first time I contribute to Jenkins code. I would like to add a new build step option to Jenkins (Like the "Execute shell" or "Invoke Ant" options). Where are these build steps kept? In the Jenkins core or is there a plugin that manages them? </p>
  
  <p>Any tips on how to add a new build step capability to Jenkins and where to start would be appreciated.</p>