To support multi-line Chinese issue, node-github need to be the latest
version, but npm won't get it by default. Modify it to get latest
version on github.

Fixed captcha error: wrong captcha won't make the mail sent now.
Mail content translate to html version. Now the issue content can be
seen in the mail.
Move some parameters to configure file, using conf.get("XXX") to
retrieve it.

To do:
  More readable mail content
  Code alignment (tab=> 2 space)