title: Query grants for a table in postgres
body: <p>How can I query all GRANTS granted to an object in postgres?</p>
  
  <p>For example I have table "mytable":</p>
  
  <pre><code>GRANT SELECT, INSERT ON mytable TO user1
  GRANT UPDATE ON mytable TO user2 
  </code></pre>
  
  <p>I need somthing which gives me:</p>
  
  <pre><code>user1: SELECT, INSERT
  user2: UPDATE
  </code></pre>