Woodman crashed when message to log to console ended with an object

Same bug as in #32: the console appender also expected the final
bit to send to the console to be a string and not to be an object.
However, in browser environments, Woodman typically send objects
as-is to the console.

lib/appenders/consoleappender.js

@@ -19,6 +19,7 @@ if (typeof define !== 'function') {
 
 define(function (require) {
   var Appender = require('../appender');
+  var utils = require('../utils');
 
   /**
    * Definition of the Appender class
@@ -67,7 +68,9 @@ define(function (require) {
       });
       if (message) {
         lastMsg = message[message.length-1];
-        if (lastMsg && (lastMsg.lastIndexOf('\n') === lastMsg.length - 1)) {
+        if (lastMsg &&
+            utils.isString(lastMsg) &&
+            (lastMsg.lastIndexOf('\n') === lastMsg.length - 1)) {
           message[message.length-1] = lastMsg.substring(0, lastMsg.length - 1);
         }
       }