title: Error installing holidays gem
body: <p>I'm receiving the following error when trying to install the holidays gem:</p>
  
  <pre><code># gem install holidays
  Fetching: holidays-1.0.4.gem (100%)
  ERROR:  Error installing holidays:
          holidays requires holidays (&gt;= 0)
  </code></pre>
  
  <p>I'm not a ruby guy, just installing some deps for <a href="http://www.redminebacklogs.net/en/installation/" rel="nofollow noreferrer">Redmine Backlogs</a> plugin.</p>
  
  <p>Versions and environment:</p>
  
  <pre><code># gem -v
  1.8.10
  
  # ruby -v
  ruby 1.8.7 (2010-06-23 patchlevel 299) [i386-linux]
  
  CentOS Linux release 6.0 (Final)
  # uname -r
  2.6.32-71.29.1.el6.i686
  </code></pre>