code: public void set(String key, String value)
  	{
  		String urlKey = urlEncode(key);
  		checkPreferenceKeyLength(urlKey);
  		checkPreferenceValueLength(value);
  
  		osm.makeAuthenticatedRequest(USERPREFS + urlKey, "PUT", new PlainTextWriter(value));
  	}
docs: Sets the given preference key to the given preference value.
  
  @param key preference to set. Must be less than 256 characters.
  @param value preference to set. Must be less than 256 characters.
  
  @throws OsmAuthorizationException if this application is not authorized to change the
  user's preferences. (Permission.CHANGE_PREFERENCES)