Improve String#casecmp? spec and use String literals when possible
Improve String#casecmp? spec and use String literals when possible

eregon/rubyspec,ruby/spec,ruby/spec,ruby/rubyspec,nobu/rubyspec,sgarciac/spec,eregon/rubyspec,ruby/rubyspec,ruby/spec,eregon/rubyspec,nobu/rubyspec,sgarciac/spec,nobu/rubyspec,sgarciac/spec