Don't automatically require awesome_print

It patches core classes (such as String) to add colorization methods
like `red` which we can't disable the same way we can with the
Colorization gem.

Gemfile

@@ -247,7 +247,7 @@ group :development, :test do
   gem 'byebug', platform: :mri
   gem 'pry-rails'
-  gem 'awesome_print', '~> 1.2.0'
+  gem 'awesome_print', '~> 1.2.0', require: false
   gem 'fuubar', '~> 2.0.0'
   gem 'database_cleaner', '~> 1.4.0'