Update Rakefile to no longer use #{RUBY}, which is no longer defined by default.
Update Rakefile to no longer use #{RUBY}, which is no longer defined by default.

liangsun/discount,liangsun/discount,liangsun/discount,liangsun/rdiscount,liangsun/rdiscount,liangsun/discount,liangsun/rdiscount,liangsun/rdiscount,liangsun/discount