title: Rrdkit - Error while using install_github/devtools/timeout issue
body: <p><strong>System :</strong> Linux - CentOS 6.5</p>
  
  <p><strong>R Version :</strong> 3.2.3 (64 bit)</p>
  
  <p>I have the same Error exposed <a href="https://stackoverflow.com/questions/31311872/error-while-using-install-github-devtools-timeout-issue">here</a> :</p>
  
  <pre><code>&gt;devtools::install_github("pauca/rrdkit/rrdkit")
   Downloading GitHub repo pauca/rrdkit@master
   from URL https://api.github.com/repos/pauca/rrdkit/zipball/master
   Error in curl::curl_fetch_memory(url, handle = handle) : 
   Timeout was reached
  
  &gt;traceback()
  13: .Call(R_curl_fetch_memory, url, handle)
  12: curl::curl_fetch_memory(url, handle = handle)
  11: request_fetch.write_memory(req$output, req$url, handle)
  10: request_fetch(req$output, req$url, handle)
  9: request_perform(req, hu$handle$handle)
  8: httr::HEAD(src_submodules, , auth)
  7: github_has_remotes(x, auth)
  6: remote_download.github_remote(remote, quiet = quiet)
  5: remote_download(remote, quiet = quiet)
  4: FUN(X[[i]], ...)
  3: vapply(remotes, install_remote, ..., FUN.VALUE = logical(1))
  2: install_remotes(remotes, quiet = quiet, ...)
  1: devtools::install_github("pauca/rrdkit/rrdkit")
  </code></pre>
  
  <p>I tested maddy2u's solution but it does not work on my station with <code>options(download.file.method = "wget")</code> or <code>options(download.file.method = "libcurl")</code>. I tried a lot of things but I have no ideas to solve that.</p>
  
  <p>Any help is welcome and thanks in advance.</p>