Set default ruby and gem versions to 1.9.1 in huginn_production

If ruby is set to default system version, the environment
provisioned with huginn_production fails to process events.

Also, the default environment misses rubygems. Here is what
I see in dj-1.log:

`require': no such file to load -- rubygems (LoadError)

This changeset will update the default system ruby to 1.9.1 and
install rubygems package.