change twitch challenge into youtube challenge and update about page removing twitch

server/views/resources/about.jade

@@ -51,9 +51,9 @@ block content
                         a(href='//medium.freecodecamp.com', target='_blank') Our Medium publication
                 tr
                     td.text-center
-                        i.fa.fa-twitch
+                        i.fa.fa-youtube
                     td
-                        a(href="//twitch.tv/freecodecamp", target='_blank') Our Twitch.tv channel
+                        a(href="//youtube.com/freecodecamp", target='_blank') Our YouTube channel
                 tr
                     td.text-center
                         i.fa.fa-reddit
@@ -221,10 +221,6 @@ block content
                     td Video challenge curriculum
                     td
                         a(href='https://gitter.im/BrianaMarie' target='_blank') @BrianaMarie
-                tr
-                    td Twitch.tv channel
-                    td
-                        a(href='https://gitter.im/Septimus' target='_blank') @Septimus
                 tr
                     td Youtube channel
                     td