Adding an Object node to the sandbox of a function node

Permit the user of the sandbox to log using the Function Node.
Test provided and working.

Fix Display warning message in the debug log
Before they were displayed as error instead of warning

nodes/core/core/80-function.html

@@ -39,6 +39,13 @@
     <p>The message is passed in as a JavaScript object called <code>msg</code>.</p>
     <p>By convention it will have a <code>msg.payload</code> property containing
        the body of the message.</p>
+    <p>If your node need to log anything use the <code>node</code> object:
+        <ul>
+            <li>Info: <code>node.log(msg);</code></li>
+            <li>Warning: <code>node.warn(msg);</code></li>
+            <li>Error: <code>node.error(msg);</code></li>
+        </ul>
+    </p>
     <p>The function should return the messages it wants to pass on to the next nodes
     in the flow. It can return:</p>
     <ul>