Loosen the pinning on "ohai"

Ohai requirement of ~> 8.0 is incompatible with Chef 13 or newer.

Unpin the requirement a little to allow for Ohai up to 14.x, as for
omnibus's needs the Ohai API should be stable up through Chef/Omnibus 14

As we may now resolve to a dependency that requires ruby >= 2.3, also
bump Omnibus's minimum required ruby >= 2.3, and drops the 2.2 testing
from appveyor and travis.

Signed-off-by: Richard Clamp <richardc@unixbeard.net>

.travis.yml

@@ -1,6 +1,5 @@
 sudo: false
 rvm:
-  - 2.2.7
   - 2.3.4
   - 2.4.1
 bundler_args: "--jobs 7 --without docs local"

appveyor.yml

@@ -8,7 +8,6 @@ environment:
   matrix:
     - RUBY_VERSION: 24
     - RUBY_VERSION: 23
-    - RUBY_VERSION: 22
 
 clone_folder: c:\projects\omnibus
 clone_depth: 1

omnibus.gemspec

@@ -13,7 +13,7 @@ Gem::Specification.new do |gem|
   gem.description    = gem.summary
   gem.homepage       = "https://github.com/chef/omnibus"
 
-  gem.required_ruby_version = ">= 2.2"
+  gem.required_ruby_version = ">= 2.3"
 
   gem.files = %w{ LICENSE README.md Rakefile Gemfile } + Dir.glob("*.gemspec") + Dir.glob("{bin,lib,resources,spec}/**/*")
   gem.bindir = "bin"
@@ -26,7 +26,7 @@ Gem::Specification.new do |gem|
   gem.add_dependency "cleanroom",        "~> 1.0"
   gem.add_dependency "ffi-yajl",         "~> 2.2"
   gem.add_dependency "mixlib-shellout",  "~> 2.0"
-  gem.add_dependency "ohai",             "~> 8.0"
+  gem.add_dependency "ohai",             ">= 8.6.0.alpha.1", "< 15"
   gem.add_dependency "ruby-progressbar", "~> 1.7"
   gem.add_dependency "thor",             "~> 0.18"
   gem.add_dependency "license_scout",    "~> 1.0"