Point to github/ruby/rake
backport from ruby/ruby
Use array-form sh arguments in PackageTask
Use array-form sh arguments in SshPublisher
Use array-form sh arguments in DSL documentation
Improve FileUtils#sh documentation
Merge pull request #1 from zzak/master

Point to github/ruby/rake
Merge pull request #2 from hsbt/backport-from-ruby-trunk

Backport from ruby/ruby
backport r43265 from ruby/ruby