Add frozen string literal comment to all Ruby files

Gemfile

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
 gemspec
 

Rakefile

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rake'
 require 'rake/testtask'
 

bundler.d/realm_ad_plugin.rb

@@ -1,2 +1,4 @@
+# frozen_string_literal: true
+
 gem 'smart_proxy_realm_ad_plugin'
 gem 'radcli'

lib/smart_proxy_realm_ad/configuration_loader.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Proxy::AdRealm
   class ConfigurationLoader
     def load_classes

lib/smart_proxy_realm_ad/plugin.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'smart_proxy_realm_ad/version'
 
 module Proxy::AdRealm

lib/smart_proxy_realm_ad/provider.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'proxy/kerberos'
 require 'radcli'
 require 'digest'

lib/smart_proxy_realm_ad/version.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Proxy
   module AdRealm
     VERSION = '0.1'.freeze

lib/smart_proxy_realm_ad_plugin.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'smart_proxy_realm_ad/configuration_loader'
 require 'smart_proxy_realm_ad/plugin'
 

smart_proxy_realm_ad_plugin.gemspec

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require File.expand_path('../lib/smart_proxy_realm_ad/version', __FILE__)
 require 'date'
 

test/ad_provider_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rubygems'
 require 'test_helper'
 require 'smart_proxy_realm_ad/provider'

test/internal_api_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 require 'rack/test'
 require 'realm/configuration_loader'

test/test_helper.rb

@@ -1,7 +1,9 @@
+# frozen_string_literal: true
+
 require 'test/unit'
 require 'mocha/setup'
 
 require 'smart_proxy_for_testing'
 
 # create log directory in our (not smart-proxy) directory
-FileUtils.mkdir_p File.dirname(Proxy::SETTINGS.log_file)
+FileUtils.mkdir_p File.dirname(Proxy::SETTINGS.log_file)

test/test_radcli.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'radcli'
 
 # Connect using password