Fix CSP for Intercom

Author: durran

src/app/index.html

@@ -55,7 +55,8 @@
         https://share.intercom.io
         https://www.youtube.com
         https://player.vimeo.com
-        https://fast.wistia.net;
+        https://fast.wistia.net
+        https://intercom-sheets.com;
       script-src
         'self'
         https://app.intercom.io