chruby v0.3.9 with up-to-date options

• chruby v0.3.9
• Google Perftools v2.3
• LibYAML v0.1.7
• RSpec 3
• Serverspec 2.0

It also adds Ubuntu 16.04 to the kitchen integration tests with optional Chef v12, and the recent releases of Ruby (2.3 and 2.4).