Update Gemfile/gemspec dependencies for Rails 5/master

Gemfile

@@ -11,11 +11,13 @@ version = ENV['RAILS_VERSION'] || '4.2'
 
 if version == 'master'
   gem 'rack', github: 'rack/rack'
+  gem 'arel', github: 'rails/arel'
   git 'https://github.com/rails/rails.git' do
     gem 'railties'
     gem 'activesupport'
     gem 'activemodel'
     gem 'actionpack'
+    gem 'activerecord', group: :test
     # Rails 5
     gem 'actionview'
   end
@@ -27,6 +29,7 @@ else
   gem 'activesupport', gem_version
   gem 'activemodel', gem_version
   gem 'actionpack', gem_version
+  gem 'activerecord', gem_version, group: :test
 end
 
 # https://github.com/bundler/bundler/blob/89a8778c19269561926cea172acdcda241d26d23/lib/bundler/dependency.rb#L30-L54
@@ -36,11 +39,9 @@ end
 gem 'tzinfo-data', platforms: (@windows_platforms + [:jruby])
 
 group :test do
-  gem 'activerecord'
   gem 'sqlite3',                          platform: (@windows_platforms + [:ruby])
   gem 'activerecord-jdbcsqlite3-adapter', platform: :jruby
 
-  gem 'minitest-reporters', require: false, group: :development
   gem 'codeclimate-test-reporter', require: false
   gem 'simplecov', '~> 0.10', require: false, group: :development
 end

active_model_serializers.gemspec

@@ -41,10 +41,16 @@ Gem::Specification.new do |spec|
     # 'minitest'
     # 'thread_safe'
 
+  spec.add_development_dependency 'activerecord', rails_versions
+    # arel
+    # activesuport
+    # activemodel
+
   # Soft dependency for pagination
   spec.add_development_dependency 'kaminari', ' ~> 0.16.3'
   spec.add_development_dependency 'will_paginate', '~> 3.0', '>= 3.0.7'
 
   spec.add_development_dependency 'bundler', '~> 1.6'
   spec.add_development_dependency 'timecop', '~> 0.7'
+  spec.add_development_dependency 'minitest-reporters'
 end