appropriating Shailen's excellent Futures intro into tutorial

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

 ---
 layout: default
 title: "Get Input from a Form"
 description: "Using HTML forms and input elements to send data to a server"
 has-permalinks: true
 tutorial:
   id: forms
 next: indexeddb/
 next-title: "Use IndexedDB"
 prev: fetchdata/
@@ skipping 44 matching lines @@
 including text fields, text areas, radio buttons, and checkboxes.
 HTML5 adds more specialized input elements such
 as email and password fields,
 color pickers, date and time widgets, and range elements.
 
 The main example in this tutorial contains a client and a server.
 The client uses Polymer to present its user interface
 (a form with many kinds of input elements),
 and keep the interface in sync with Dart data.
 The client and server communicate using
-several classes from the core Dart library,
+several classes from various Dart libraries,
 including streams, Futures, HttpRequest, and so on.
 The server uses CORS headers to allow cross-origin requests.
 
 <aside class="alert alert-info" markdown="1">
   <strong>Note:</strong>
   This tutorial assumes that you have read
-  [Define a Custom Element](/docs/tutorials/polymer-intro/)
+  [Define a Custom Element](/docs/tutorials/polymer-intro/),
+  [Use Future Based APIs](/docs/tutorials/futures/),
   and [Fetch Data Dynamically](/docs/tutorials/fetchdata/)
-  and are familiar with Polymer, JSON, and HttpRequest.
+  and are familiar with Polymer, Futures, JSON, and HttpRequest.
 </aside>
 
 
 * [About forms, generally](#about-forms)
 * [About the slambook example, specifically](#about-the-slambook-example)
 * [Submitting a form](#submitting-a-form)
 * [Resetting a form](#resetting-a-form)
 * [Creating a server and listening on a port](#creating-a-server)
 * [Handling OPTIONS requests](#handling-options-requests)
 * [Setting CORS headers](#setting-cors-headers)
@@ skipping 882 matching lines @@
 ###What next?
 
 The next tutorial,
 [Use IndexedDB](/docs/tutorials/indexeddb),
 describes how to save data on the client
 in the browser's Indexed Database.
 
 {% endcapture %}
 
 {% include tutorial.html %}