Rails 4 removed the `BestStandardsSupport` middleware, because
supposedly a HTML5 doctype accomplishes the same thing. But not
quite -- without X-UA-Compatible, the UI for changing compatibility
mode is still visible, and users can get themselves into a bad state
(see https://github.com/openstreetmap/openstreetmap-website/pull/498#issuecomment-
28483550)
<head>
+ <meta http-equiv="X-UA-Compatible" content="IE=edge"/>
<meta name="viewport" content="width=device-width, minimum-scale=1.0, maximum-scale=1.0"/>
<%= javascript_include_tag "application" %>
<!--[if lt IE 7]><%= javascript_include_tag "pngfix" %><![endif]--> <!-- thanks, microsoft! -->