Now selects first element in series rather than 0th element - old way could cause problems when the dataframe being drawn doesn't start at index 0 and starts at a higher number. Happened to me :P

I was getting error that kwargs is undefined:
```NameError Traceback (most recent call last)
<ipython-input-173-30fb7f3aeb2e> in <module>()
 9 facet_row='cut',
 10 color_name='depth',
---> 11 facet_col='z'
 12 
 13 )
/home/alishobeiri/anaconda2/lib/python2.7/site-packages/plotly/figure_factory/_facet_grid.pyc in create_facet_grid(df, x, y, facet_row, facet_col, color_name, colormap, color_is_cat, facet_row_labels, facet_col_labels, height, width, trace_type, scales, dtick_x, dtick_y, show_boxes, ggplot2, binsize, **kwargs)
 867 facet_row_labels, facet_col_labels, trace_type,
 868 flipped_rows, flipped_cols, show_boxes, marker_color,
--> 869 kwargs_trace, kwargs_marker
 870 )
 871 
/home/alishobeiri/anaconda2/lib/python2.7/site-packages/plotly/figure_factory/_facet_grid.pyc in _facet_grid_color_numerical(df, x, y, facet_row, facet_col, color_name, colormap, num_of_rows, num_of_cols, facet_row_labels, facet_col_labels, trace_type, flipped_rows, flipped_cols, show_boxes, marker_color, kwargs_trace, kwargs_marker)
 414 type=trace_type,
 415 showlegend=False,
--> 416 **kwargs
 417 )
 418 fig.append_trace(trace, row_count + 1, col_count + 1)
NameError: global name 'kwargs' is not defined ```
Thought it might be because kwargs should actually be kwards_trace - not sure tho