The npmjs.org link has moved (https)

Change the link to https rather than http, otherwise you get this:

(syte)manavo:~ manavo$ curl http://npmjs.org/install.sh | sudo sh
  % Total    % Received % Xferd  Average Speed   Time    Time     Time  Current
                                 Dload  Upload   Total   Spent    Left  Speed
100    85    0    85    0     0    222      0 --:--:-- --:--:-- --:--:--   611
sh: line 1: syntax error near unexpected token `newline'
sh: line 1: `<html>Moved: <a href="https://npmjs.org/install.sh">https://npmjs.org/install.sh</a>'