Fix admin in IE

Ensure Internet Explorer uses the latest engine to prevent missing
icons and layout issues.

Author: wcharlton

app/views/layouts/rails_admin/application.html.haml

@@ -1,6 +1,7 @@
 !!! 5
 %html
   %head
+    %meta{content: "IE=edge", "http-equiv" => "X-UA-Compatible"}
     %meta{content: "text/html; charset=utf-8", "http-equiv" => "Content-Type"}
     %meta{content: "NONE,NOARCHIVE", name: "robots"}
     = csrf_meta_tag