title: adjusting x_axis_label or y_axis_label font/font size (Bokeh)
body: <p>Is there a way to adjust <code>x_axis_label</code> and <code>y_axis_label</code> font/font size in Bokeh (0.70)?  I am aware of a way to adjust title font size with the <code>title_text_font_size</code> property, with:</p>
  
  <pre><code>figure (..., title_text_font_size="12pt")
  </code></pre>
  
  <p>Is there a way to then specify something like:</p>
  
  <pre><code>figure (..., x_axis_label_text_font_size='10pt')
  </code></pre>
  
  <p>(using the convention of <code>&lt;name&gt;</code>_text_font_size) to indicate the font size property.  The above did not work.  If this is not present, could someone give some pointers as to how to make this sort of adjustment in the cofeescript + API-side of things, so can contribute back to the project?  Thanks</p>