title: Logging values of variable with kivy.logger
body: <p>I want to log the value of a variable using kivy.logger in file.</p>
  
  <p>I added the following lines to my code:</p>
  
  <pre><code>from kivy.logger import Logger
  
  Logger.debug('EZS-2G:  element: %s', str(element))
  </code></pre>
  
  <p>the following line appears in my IDE (Atom):</p>
  
  <pre><code>[DEBUG             ] [EZS-2G      ]  element: tab_0_obj_sensor
  </code></pre>
  
  <p>but the log file under C:\Users\username.kivy\logs says only:</p>
  
  <pre><code>[DEBUG             ] EZS-2G: %s
  </code></pre>
  
  <ul>
  <li>How could I write the correct value into the logfile instead of %s?</li>
  <li>How could I change the folder of the log files? After the packaging (creating a "myapp/myapp.exe") I want to read the logs in the myapp/logs folder, instead of the "C:\Users\username.kivy\logs" folder? </li>
  </ul>
  
  <p>OS: Win7 ; Python: 3.4 ; Kivy: 1.9</p>