docs(favicon): Added favicon to ui-grid.info

Added a link tag to both the home page and the customizer to use existing favicon.

Issue #3899

Author: Portugal, Marcelo

misc/site/customizer/index.html

@@ -10,6 +10,7 @@
   <link rel="stylesheet" href="/docs/css/bootstrap-flatly.min.css" />
   <link rel="stylesheet" href="//netdna.bootstrapcdn.com/font-awesome/4.0.3/css/font-awesome.min.css" />
   <link rel="stylesheet" href="/css/site.css" />
+  <link rel="shortcut icon" href="/docs/favicon.ico" />
   <!--<link rel="stylesheet" href="/release/ui-grid-unstable.css" />-->
   <style>
     .compiled-css {

misc/site/index.html

@@ -13,6 +13,7 @@
   <link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/font-awesome/4.5.0/css/font-awesome.min.css" />
   <link rel="stylesheet" href="/css/site.css" />
   <link rel="stylesheet" href="//ui-grid.info/release/ui-grid-unstable.min.css" />
+  <link rel="shortcut icon" href="/docs/favicon.ico" />
   <script>
     ((window.gitter = {}).chat = {}).options = {
       room: 'angular-ui/ui-grid'