Run rubocop as part of default rake task

I try to always run the default rake task locally before I push any
changes to GitHub. I find it frustrating if I do that and there are no
failures, but then I see rubocop failures in the CI build. I'd prefer to
see them locally.

Since it doesn't look as if `.circleci/config.yml` is using any rake
tasks, this shouldn't affect the CI build.

Author: floehopper

lib/tasks/default.rake

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+return if Rails.env.production?
+
+Rake::Task[:default].clear_prerequisites
+task default: %i[rubocop spec]

lib/tasks/rubocop.rake

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+return if Rails.env.production?
+
+require 'rubocop/rake_task'
+RuboCop::RakeTask.new