#48 + assorted boilerplate build fixes

[hartmantis]

• Put a guard on the shell-init resource to not run on Windows (via Feature no omnijack call when package_url defined #48)
• Don't install Omnijack or query the Omnitruck API when a package_url is provided (via Feature no omnijack call when package_url defined #48)
• Update Kitchen config to most recent Vagrant boxes
• Move the Travis OS X testing to use kitchen-localhost
• Update assorted boilerplate stuff (add a CoC, fix new RuboCop offenses, use HTTPS on all badges, s/getchef.com/chef.io, etc.)

[coveralls]

Coverage remained the same at 100.0% when pulling 628ac3b on feat-no-omnijack into 2abce6c on master.

[coveralls]

Coverage remained the same at 100.0% when pulling 3e26e3a on feat-no-omnijack into 2abce6c on master.

[coveralls]

Coverage remained the same at 100.0% when pulling 3e26e3a on feat-no-omnijack into 2abce6c on master.