migrate to travis new infrastructure

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@51706 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

.travis.yml

@@ -16,6 +16,10 @@
 #
 # is also a good place to look at.
 
+# new infrastructure
+# http://docs.travis-ci.com/user/migrating-from-legacy/
+sudo: false
+
 # Language specification.
 language: c