Reza,
Noticed you comment on the blog as well, answering it here. One of our other users pointed out that on ubuntu we need a few additional steps. We are in the process of adding to docs too. Please try this.
You need to add the slc path to your .bashrc file like this:
First add this to the end of the .bashrc:
export PATH=/root/npm/bin:$PATH
Then reset your console source with this:
$ source .bashrc
That works otherwise slc is registered to something called heimdal-multidev
"npm install -g strongloop" installs fine, but does not register a path.
and let us know.