title: How to configure an extra/different migrations folder
body: <p>A colleague and I are working in different projects that share some models. So, we are sharing the models through a git submodule.</p>
  
  <p>Additionally, we'd like to be able to also share migrations:</p>
  
  <p>In this way, my colleague's migrations would be in the folder <code>db/migrate/other_db</code> of my project.</p>
  
  <p>How can I configure rails migrations to also run the migrations in this extra folder?</p>