title: application wide global variable
body: <p>In <strong>Rails</strong>, where should I define the variable which can be recognized by every layer of Rails stacks. </p>
  
  <p>For example, I would like to have a <code>CUSTOMER_NAME='John'</code> variable which can be accessed in <strong>helper</strong>, <strong>rake</strong> task, <strong>controller</strong> and <strong>model</strong>. Where should I define this variable in <strong>Rails</strong> app?</p>
  
  <p>I am using <strong>Rails v2.3.2</strong></p>