title: Geopandas save as KML doesn't include columns
body: <p>I tried to save the geopandas into KML.</p>
  
  <p>Below are my code.</p>
  
  <pre><code>import fiona
  fiona.supported_drivers['KML'] = 'rw'
  gp.io.file.fiona.drvsupport.supported_drivers['KML'] = 'rw'
  a = df_geom[['Geohash_8','Geohash_7','Final Action (Coverage)','geometry']].head(3)
  a.to_file('test.kml',driver='KML')
  </code></pre>
  
  <p>When I open in Google Earth, the polygon does not displaying 'Final Action (Coverage)'.</p>