title: Two space line break doesnt work on GitHub when converting .rmd to .md using github_document
body: <p>I was trying to convert an <code>.rmd</code> document to <code>.md</code> to upload on GitHub using <code>output: github_document</code> in my YAML header.</p>
  
  <p>Apparently, the conversion does not respect the two or more spaces I used in my .rmd file to force a linebreak. </p>
  
  <p><strong>Example:</strong> I created this little <code>.rmd</code> file:</p>
  
  <pre><code>---
  title: "Line Break issue"
  output: github_document
  ---
  
  1.  My First point  
  Another point right below  
  and more
  
  1.  My second point
  </code></pre>
  
  <p>I used two spaces to force a break between "My first Point" and "Another point..." and "and more". When I knit, the preview is fine, however, when I upload to GitHub the linebreaks are only adequately respected in the <code>.rmd</code> file as you can see <a href="https://github.com/M-E-Steiner/MyDesk/blob/master/line_break_question.rmd" rel="nofollow">here</a> but apparently gone in the <code>.md</code> file as you can <a href="https://github.com/M-E-Steiner/MyDesk/blob/master/line_break_question.md" rel="nofollow">here</a>.</p>
  
  <p>Why is that?</p>
  
  <p>EDIT:</p>
  
  <p>I am using <code>rmarkdown_0.9.6</code> within RStudio <code>Version 0.99.1130</code> on <code>R 3.3.0</code>.</p>