Update librarian script

**In short:** Latest librarian fixes are under `librarian-puppet-maestrodev` and not `librarian-puppet`

I tried to add https://github.com/willdurand/puppet-nodejs manually to puppet generate via website, but got error (solved here: https://github.com/rodjek/librarian-puppet/pull/94#issuecomment-30318287). Fix is not available via `gem install` (see: https://github.com/rodjek/librarian-puppet/issues/149#issuecomment-31340416).

I changed gem name and removed `if` clause, to ensure librarian is up to date to prevent similar cases.

I wonder if `touch /.puphpet-stuff/librarian-puppet-installed` should also be removed as it is only used in begining of same file to check some stuff (late night here, heh).