title: Add module name in winston log entries
body: <p>Is there a possibility to save the current module name in order to be printed automatically in <a href="https://www.npmjs.com/package/winston" rel="noreferrer">winston</a> log entries when they are called later?</p>
  
  <p>Currently, when I want to print the module name in logs, I have to add it manually:</p>
  
  <pre><code>var logHeader = 'mymodule'
  
  log.info(logHeader + 'Hello')
  </code></pre>
  
  <p>For example, with <a href="https://www.npmjs.com/package/debug" rel="noreferrer">debug</a>, you can do (ignore the log format feature <code>%s</code> for now):</p>
  
  <pre><code>var debug = require('debug')('http')
    , name = 'My App'
  
  debug('booting %s', name);
  </code></pre>
  
  <p>This will prin <code>http</code> prefix before the log:</p>
  
  <blockquote>
    <p>http booting My App</p>
  </blockquote>
  
  <p>Can this be done in winston? I have searched in the documentation but I couldn't find anything relevant.</p>