fix cell execution in firefox, closes #3447

location.origin is specific to WebKit only. The fix is to use a
combination of location.protocol and location.host
Merge pull request #3453 from ivanov/fix-3447

fix websocket connection in old Firefox

location.origin is a too recent addition.

closes #3447
Notice for users who disable javascript
use less.css for the style of the noscript message
Merge pull request #3456 from ivanov/noscript

Add notice for users who disable javascript