Add charset to error pages

closes #7092

Changelog.md

@@ -6,7 +6,7 @@
 * Make the session cookies HttpOnly again [#7041](https://github.com/diaspora/diaspora/pull/7041)
 * Invalidate sessions with invalid CSRF tokens [#7050](https://github.com/diaspora/diaspora/pull/7050)
 * Liking a post will no longer update its interacted timestamp [#7030](https://github.com/diaspora/diaspora/pull/7030)
-* Improve W3C compliance [#7068](https://github.com/diaspora/diaspora/pull/7068) [#7082](https://github.com/diaspora/diaspora/pull/7082) [#7091](https://github.com/diaspora/diaspora/pull/7091)
+* Improve W3C compliance [#7068](https://github.com/diaspora/diaspora/pull/7068) [#7082](https://github.com/diaspora/diaspora/pull/7082) [#7091](https://github.com/diaspora/diaspora/pull/7091) [#7092](https://github.com/diaspora/diaspora/pull/7092)
 * Load jQuery in the head on mobile [#7086](https://github.com/diaspora/diaspora/pull/7086)
 
 ## Bug fixes

app/views/layouts/error_page.haml

@@ -3,6 +3,7 @@
   %head
     %title= page_title yield(:page_title)
 
+    %meta{charset:  "utf-8"}
     %link{rel: "shortcut icon", href: image_path("favicon.png")}
     %link{rel: "apple-touch-icon", href: image_path("apple-touch-icon.png")}