Only ship the required libs in the gem artifact (#172)

There's no need to ship the cookbook and the test files in the gem
artifact. This ships just the necessary files to include chef-sugar.
Signed-off-by: Tim Smith <tsmith@chef.io>

chef-sugar.gemspec

@@ -19,9 +19,7 @@ Gem::Specification.new do |spec|
 
   spec.required_ruby_version = '>= 2.2.2'
 
-  spec.files         = `git ls-files`.split($/)
-  spec.executables   = spec.files.grep(%r{^bin/}) { |f| File.basename(f) }
-  spec.test_files    = spec.files.grep(%r{^(test|spec|features)/})
+  spec.files         = %w{LICENSE} + Dir.glob("lib/**/*", File::FNM_DOTMATCH).reject { |f| File.directory?(f) }
   spec.require_paths = ['lib']
 
   spec.add_development_dependency 'bundler', '~> 1.3'