Added new server/cmdline/io programmers' guide.

src/site/docs/tutorials/remove-elements/index.markdown

 ---
-layout: default
+layout: tutorial
 title: "Remove DOM Elements"
 description: "Remove a child element from the DOM"
 has-permalinks: true
 tutorial:
   id: remove-elements
 next: shared-pkgs/
 next-title: "Install Shared Packages"
 prev: add-elements/
 prev-title: "Add Elements to the DOM"
 ---
@@ skipping 227 matching lines @@
 
 * One of those packages is Polymer.dart,
 which makes manipulating the DOM even easier
 with data binding, templates, and declarative event handlers.
 Check out [Define a Custom Element](/docs/tutorials/polymer-intro)
 for an introduction to Polymer.
 
 {% endcapture %}
 
 {% include tutorial.html %}