Skip exit status specs on 1.8.7

Author: deivid-rodriguez

spec/script_exit_status_spec.rb

@@ -26,4 +26,4 @@ def thor_command(command)
   it "a command that does not raise a Thor::Error exits with a status of 0" do
     expect(thor_command("ok")).to eq(0)
   end
-end
+end if RUBY_VERSION > "1.8.7"