Added a capitalize filter

Author: florianv

demo.html

@@ -104,11 +104,13 @@ <h3>list</h3>
     <h3>list(" ")</h3>
     {{colors | list(" ")}}
 
+    <h3>capitalize</h3>
+    {{greeting | capitalize}}
+
 </template>
   <script>
 	var template = document.getElementById('view');
 	var phones = [{'name':'Nexus S','snippet':'Fast just got faster with Nexus S.','age':1},{'name':'Motorola XOOM with Wi-Fi','snippet':'The Next, Next Generation tablet.','age':2},{'name':'MOTOROLA XOOM','snippet':'The Next, Next Generation tablet.','age':3}];
-	var template = document.getElementById('view');
 	template.phones = phones;
 	template.orderProp = 'age';
 	template.colors = ['red','green','blue','yellow'];

filter-capitalize.js

@@ -0,0 +1,9 @@
+/**
+ * Capitalize a string (transform its first letter to uppercase and the rest to lowercase)
+ * @param  {string} string
+ * @return {string} the capitalized string
+ */
+PolymerExpressions.prototype.capitalize = function (string) {
+	string = string.toLowerCase();
+	return string.charAt(0).toUpperCase() + string.slice(1);
+};

polymer-filters.html

@@ -19,6 +19,7 @@
 <script src="filter-length.js"></script>
 <script src="filter-list.js"></script>
 <script src="filter-limitTo.js"></script>
+<script src="filter-capitalize.js"></script>
 
 <!--
 A collection of filters for formatting values of [Polymer expressions](http://www.polymer-project.org/docs/polymer/expressions.html) for display to users.
@@ -176,6 +177,12 @@
 
 > something, somethingelse, etc
 
+####Capitalize
+
+    {{ "Hello World!" | capitalize }}
+
+> Hello world!
+
 @element polymer-filters
 @blurb A collection of Polymer filters for formatting values of expressions for display to users
 @homepage http://github.com/addyosmani/polymer-filters