title: gps conversion of Time object
body: <p>I am trying to  figure out why when a time object is converted to GPS time, it becomes an array rather than remaining as a Time object. Example:</p>
  
  <pre><code>from astropy.time import Time
  
  times = Time([56701, 56702], format="mjd", scale="tdb")
  times.gps
  
  Out: array([  1.07628475e+09,   1.07637115e+09])
  </code></pre>
  
  <p>While conversion to other times gives:</p>
  
  <pre><code>times.utc
  Out: &lt;Time object: scale='utc' format='mjd' value=[ 56700.9992224  56701.9992224]&gt;
  </code></pre>
  
  <p>Which I believe is the intended behaviour.</p>