title: Insert padding so that points do not overlap with y or x-axis
body: <p>I have the created this plot in D3: <a href="http://bl.ocks.org/cddesja/aee65f660c24cb2144fd" rel="noreferrer">http://bl.ocks.org/cddesja/aee65f660c24cb2144fd</a></p>
  
  <p>There are two things I would like to change.</p>
  
  <p>1) I would like to make it so that none of my points overlap with the y or x-axis. I thought I could use <code>transform()</code> to create a little bit of a buffer but that creates a gap between the x and y axis lines, something I do not want. How should I do this correctly? </p>
  
  <p>2) I would like to get rid of the tick marks at the intersection of the x and y lines. I am hoping that once I move the tick marks (and subsequently the pts and lines) that these tick marks automagically disappear. I don't know if that's really true or not.</p>
  
  <p>Thanks in advance.
  Chris</p>