Merge pull request #2927 from hone/bintest_subfolders

run bintests within subfolders of bintest/

test/bintest.rb

@@ -2,7 +2,7 @@ $:.unshift File.dirname(File.dirname(File.expand_path(__FILE__)))
 require 'test/assert.rb'
 
 ARGV.each do |gem|
-  Dir["#{gem}/bintest/*.rb"].each do |file|
+  Dir["#{gem}/bintest/**/*.rb"].each do |file|
     load file
   end
 end