Link to a specific cURL error

Test Plan:
  $url = 'http://www.suraski.net/blog/index.php?/feeds/index.rss2';
  $future = new HTTPSFuture($url);
  list($status) = $future->resolve();
  echo $status->getMessage() . "\n";

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Differential Revision: https://secure.phabricator.com/D6429