title: knex how to check if current migration is the latest or not
body: <p>I am using knex for postgres migration version control. The basic idea is: 
  every time when node starts, it checks if current database migration is the latest or not. If not, then apply the latest one by <code>knex.migrate.latest().then(....)</code>. </p>
  
  <p>For example, I have a <code>init.js</code> migration file which is my current db version. Then I submit a new one <code>newMigration.js</code> and re-start server. I want the node to find the new migration and apply it.</p>
  
  <p>I know there is a <code>.currentVersion</code> function to get the current db migration version, but how can node know the newly added migration (version)?</p>
  
  <p>Please advise! Thanks!</p>