Use command instead of type to locate ruby
Use command instead of type to locate ruby

As reported in #1, "type -P ruby" fails in Ubuntu because of the
very limited sh provided (dash). Use command instead of type.

SuperNEMO-DBD/cadfaelbrew,SuperNEMO-DBD/cadfaelbrew,SuperNEMO-DBD/cadfaelbrew,SuperNEMO-DBD/cadfaelbrew