title: pass an array of values into bigquery query with pandas
body: <p>After some processing I get the following array: </p>
  
  <pre><code>users = array([u'5451709866311680', u'4660301072957440', u'6370791394377728',
     u'5121933955825664', u'4778500988862464', u'5841867648270336',
     u'4751430816628736', u'4869137213947904', u'5152642703556608',
     u'6531810976595968', u'4824167228637184', u'6058117842337792',
     u'5969360933879808', u'4764494160986112', u'5443041280131072',
     u'4846257587617792', u'5409371420884992', u'6197117949313024',
     u'6643644022915072', u'5060273861820416'], dtype=object)
  </code></pre>
  
  <p>And then I would like to query this users in another table in bigquery but I'm having issues.</p>
  
  <pre><code>query = """
  SELECT  *
  FROM games
  WHERE user_id IN %users
  """
  segment = pd.io.gbq.read_gbq(query, project_id='shared', dialect='standard)
  </code></pre>
  
  <p>Anyone knows how to proceed?</p>
  
  <p>Thank you </p>