title: Passenger could not be initialized because of this error: Option 'agents_dir' missing in file - Rails 4 + Passenger deployment
body: <p>I have been banging my head against a door trying to deploy a Rails 4 app on Ubuntu 14 + Apache2 + Passenger. I seemed to have made some progress: passenger is installed properly with the proper apache modules, my apache conf files are set up, everything is restarted, etc.. when I go to my site I get a listing of my Rails App's public directory. I investigated the logs and found the following:</p>
  
  <p><code>Passenger could not be initialized because of this error: Option 'agents_dir' missing in file '/usr/lib/ruby/vendor_ruby/phusion_passenger/locations.ini'
  </code></p>
  
  <p>I different SO post said something about mods-available stuff so here's <code>/etc/apache2/mods-available/passenger.conf</code>:</p>
  
  <p><code>&lt;IfModule mod_passenger.c&gt;
    PassengerRoot /usr/lib/ruby/vendor_ruby/phusion_passenger/locations.ini
    PassengerDefaultRuby /usr/bin/ruby
  &lt;/IfModule&gt;</code></p>
  
  <p>And <code>/etc/apache2/mods-available/passenger.load</code>:</p>
  
  <p><code>LoadModule passenger_module /usr/lib/apache2/modules/mod_passenger.so</code></p>
  
  <p>What am I doing wrong? I'm going to kiss whoever solves this, I swear.</p>