Update polymer tutorial; make directory paths match new sample structure

src/site/docs/tutorials/streams/index.markdown

 ---
 layout: tutorial
 title: "Use Streams for Data"
 description: 
   Learn how to consume single-subscriber and broadcast streams, 
   with real-world uses.
 tutorial:
   id: streams
 next: fetchdata/
 next-title: "Fetch Data Dynamically"
@@ skipping 11 matching lines @@
 * Use transformers to modify the data as it becomes available.
 * Stream has methods for skipping, selecting, filtering, and validating data.
 * Streams provide a way to respond to errors.
 
 {% endcapture %}
 
 {% capture sample_links %}
 
 
 <p markdown="1"> This tutorial features these examples
-in the `bin` directory:</p>
+in the `streams/bin` directory:</p>
 
 * feet_wet_streams.dart
 * html_streams.dart
 * http_request.dart
 
 <p>
 Don't have the source code?
 <a href="https://github.com/dart-lang/dart-tutorials-samples/archive/master.zip">
   Download it.
 </a>
@@ skipping 459 matching lines @@
 Chris Buckett is a Technical Manager for
 [Entity Group Ltd](http://www.entity.co.uk/), responsible for building and
 delivering enterprise client-server webapps, mostly with GWT, Java and .Net.
 He runs the [dartwatch.com blog](http://blog.dartwatch.com/), and has written
 the book _Dart in Action_, which is available
 at [manning.com](http://www.manning.com/buckett).
 
 {% endcapture %}
 
 {% include tutorial.html %}