Add homepage unsupported browser messages to new home page

app/templates/new-home-view.jade

@@ -1,3 +1,16 @@
+.container-fluid.text-center
+  .alert.alert-danger.lt-ie9
+    strong(data-i18n="home.no_ie") CodeCombat does not run in Internet Explorer 8 or older. Sorry!
+
+  if view.isIPadBrowser() || view.isMobile()
+    .alert.alert-danger.mobile
+      strong(data-i18n="home.no_mobile") CodeCombat wasn't designed for mobile devices and may not work!
+  else if view.isOldBrowser()
+    .alert.alert-danger.old-browser
+      strong(data-i18n="home.old_browser") Uh oh, your browser is too old to run CodeCombat. Sorry!
+      br
+      span(data-i18n="home.old_browser_suffix") You can try anyway, but it probably won't work.
+
 nav.navbar.navbar-default
   .container-fluid
     .navbar-header

app/views/NewHomeView.coffee

@@ -73,3 +73,15 @@ module.exports = class NewHomeView extends RootView
 
   onClickTeacherButton: ->
     @scrollToLink('.request-demo-row', 600)
+
+  isOldBrowser: ->
+    if $.browser
+      majorVersion = $.browser.versionNumber
+      return true if $.browser.mozilla && majorVersion < 25
+      return true if $.browser.chrome && majorVersion < 31  # Noticed Gems in the Deep not loading with 30
+      return true if $.browser.safari && majorVersion < 6  # 6 might have problems with Aether, or maybe just old minors of 6: https://errorception.com/projects/51a79585ee207206390002a2/errors/547a202e1ead63ba4e4ac9fd
+    else
+      console.warn 'no more jquery browser version...'
+    return false
+
+