Improve code to fit rubocop rules

.rubocop.yml

@@ -1,8 +1,14 @@
 inherit_from: .rubocop_todo.yml
 AllCops:
+  DisplayCopNames: true
   TargetRubyVersion: 2.4
   Include:
     - Rakefile
     - lib/**/*.rake
+  Exclude:
+    - Gemfile
+    - Appraisals
+    - rails-letsencrypt.gemspec
+    - lib/generators/lets_encrypt/templates/migration.rb
 Rails:
   Enabled: true

Gemfile

@@ -1,3 +1,4 @@
+# frozen_string_literal: true
 source 'https://rubygems.org'
 
 # Declare your gem's dependencies in lets_encrypt.gemspec.

Rakefile

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 begin
   require 'bundler/setup'
 rescue LoadError

app/jobs/lets_encrypt/application_job.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module LetsEncrypt
   class ApplicationJob < ActiveJob::Base
   end

app/models/concerns/lets_encrypt/certificate_issuable.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module LetsEncrypt
   # :nodoc:
   module CertificateIssuable

app/models/concerns/lets_encrypt/certificate_verifiable.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module LetsEncrypt
   # :nodoc:
   module CertificateVerifiable
@@ -52,9 +54,7 @@ def retry_on_verify_error(e)
       @retries ||= 0
       if e.is_a?(Acme::Client::Error::BadNonce) && @retries < 5
         @retries += 1
-        # rubocop:disable Metrics/LineLength
         logger.info "Bad nounce encountered. Retrying (#{@retries} of 5 attempts)"
-        # rubocop:enable Metrics/LineLength
         sleep 1
         verify
       else

bin/rails

@@ -1,4 +1,6 @@
 #!/usr/bin/env ruby
+# frozen_string_literal: true
+
 # This command will automatically be run when you run "rails" with Rails gems
 # installed from the root of your application.
 

config/routes.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 LetsEncrypt::Engine.routes.draw do
   get '/acme-challenge/:verification_path', to: 'verifications#show'
 end

lib/generators/lets_encrypt/register_generator.rb

@@ -26,7 +26,7 @@ def setup_environment
       end
 
       def generate_key
-        # rubocop:disable Metric/LineLength
+        # rubocop:disable Metrics/LineLength
         key_path = ask("Where you to save private key [#{LetsEncrypt.private_key_path}]:", path: true)
         # rubocop:enable Metrics/LineLength
         key_path = LetsEncrypt.private_key_path if key_path.blank?

lib/letsencrypt.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'openssl'
 require 'acme-client'
 require 'redis'
@@ -9,8 +11,8 @@
 
 # :nodoc:
 module LetsEncrypt
-  ENDPOINT = 'https://acme-v01.api.letsencrypt.org/'.freeze
-  ENDPOINT_STAGING = 'https://acme-staging.api.letsencrypt.org'.freeze
+  ENDPOINT = 'https://acme-v01.api.letsencrypt.org/'
+  ENDPOINT_STAGING = 'https://acme-staging.api.letsencrypt.org'
 
   class << self
     def client

lib/letsencrypt/engine.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module LetsEncrypt
   # :nodoc:
   class Engine < ::Rails::Engine

lib/letsencrypt/logger_proxy.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module LetsEncrypt
   # :nodoc:
   class LoggerProxy

lib/letsencrypt/redis.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module LetsEncrypt
   # :nodoc:
   class Redis

lib/letsencrypt/version.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module LetsEncrypt
   VERSION = '0.4.0'
 end

lib/rails-letsencrypt.rb

@@ -1 +1,3 @@
+# frozen_string_literal: true
+
 require 'letsencrypt'

rails-letsencrypt.gemspec

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 $:.push File.expand_path("../lib", __FILE__)
 
 # Maintain your gem's version:

spec/rails_helper.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This file is copied to spec/ when you run 'rails generate rspec:install'
 require 'spec_helper'
 ENV['RAILS_ENV'] ||= 'test'

spec/spec_helper.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This file was generated by the `rails generate rspec:install` command. Conventionally, all
 # specs live under a `spec` directory, which RSpec adds to the `$LOAD_PATH`.
 # The generated `.rspec` file contains `--require spec_helper` which will cause