layouts/partials/head-meta.html: Remove IE meta tags

Bootstrap v4 Alpha 6 removes support for IE 8 and 9 and these tags
are no longer necessary.

See: twbs/bootstrap#21483

layouts/partials/head-meta.html

@@ -1,7 +1,5 @@
 <meta charset="utf-8">
-<meta http-equiv="X-UA-Compatible" content="IE=edge">
 <meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
-{{ "<!-- The above 3 meta tags *must* come first in the head; any other head content must come *after* these tags -->" | safeHTML }}
 
 {{ template "_internal/opengraph.html" . }}
 {{ template "_internal/schema.html" . }}