public boolean isFolder() determines if the node is a
      folder.
    Parameters
None
Returns
Returns a boolean. True if the node is a folder, false otherwise.
Example
    Node node = getTestNode(session, "ClimbingVolcanoes.JPG");
    
    Log.d(TAG, "isFolder: " + node.isFolder());      
      
      Would return output such as the following:
    isFolder: false