title: How to show datepicker widget?
body: <p>I have the following code:</p>
  
  <pre><code>from bokeh.plotting import curdoc
  from bokeh.layouts import widgetbox
  from bokeh.layouts import column as bokehCol
  from bokeh.models.layouts import Column
  from bokeh.models.widgets import DatePicker
  from datetime import date
  from datetime import timedelta as td
  from datetime import datetime as dt
  from bokeh.io import output_notebook
  from bokeh.plotting import show
  
  output_notebook()
  
  crnt_date=dt.now()
  
  dt_pckr_strt=DatePicker(title='Select start of sync date',min_date=date(2017,1,1),max_date=date.today())
  
  def callback(attr,old,new):
      print(type(old))
      print('old was {} and new is {}'.format(old,new))
  
  dt_pckr_strt.on_change('value',callback)
  curdoc().add_root(bokehCol(dt_pckr_strt))
  show(widgetbox(dt_pckr_strt, width=300))
  </code></pre>
  
  <p>The output is showing weird instead of conventional datepicker. I believe it's in show function I am doing some mistake. Where am I going wrong?</p>