add Dir.mkdir
Merge pull request #341 from topazproject/tim/Dir.mkdir

Add Dir.mkdir
simpler assertion
Array#delete_at: Don't fail on negative indices
Array#delete_at: Fail on frozen
Add array/delete_at_spec.rb to Travis specs
Nitpicking
Merge pull request #344 from judofyr/array-delete_at

Implement Array#delete_at per RubySpec
link the logs
Merge branch 'master' of github.com:topazproject/topaz
Merge branch 'master' of git://github.com/topazproject/topaz