Allow JRuby to start the benchmark suite

[brianhempel]

As per the documentation:

cd runner
rake

Right now the runner uses fork, but it might not need to.

/cc @headius

[headius]

Auditing some old issues that show up in my mentions...

I believe you could use spawn now, since the fork call is simply used to get a detached process in which to exec the command.

diff --git a/runner/Rakefile b/runner/Rakefile
index 1834c27..ca33f29 100644
--- a/runner/Rakefile
+++ b/runner/Rakefile
@@ -33,7 +33,7 @@ def run_with_output(command)
   puts note
   puts "=" * note.size
 
-  Process.wait( fork { exec command } )
+  Process.wait( spawn command )
   $?.success? # return whether command succeeded or not
 end