title: adding R package for installation from Github in Dockerfile
body: <p>How must I add installation instruction for a R package using github with my Dockerfile.</p>
  
  <p>The usual command in R environment is:</p>
  
  <pre><code>devtools::install_github("smach/rmiscutils")
  </code></pre>
  
  <p>But no success so far. Tried to add github repo to installation instructions:</p>
  
  <pre><code>RUN install2.r --error \ 
      -r 'http://cran.rstudio.com' \
      -r 'http://github.com/smach/rmiscutils' 
  </code></pre>
  
  <p>But I get an error:</p>
  
  <pre><code>error in download. Status was '404 Not found'
  </code></pre>
  
  <p>Maybe using vanilla R call but can't figure the command.
  Any Hint?</p>