Add rubocop and rspec as runtime dependencies

Gemfile

@@ -3,8 +3,6 @@ source "https://rubygems.org"
 gemspec
 
 group :test do
-  gem "rspec", "~>3.2"
-  gem "rubocop", "~>0.31"
   gem "coveralls", "~>0.8", require: false
   gem "simplecov", "~>0.10", require: false
   gem "codeclimate-test-reporter", "~>0.4"

github_changelog_generator.gemspec

@@ -29,4 +29,6 @@ Gem::Specification.new do |spec|
   spec.add_runtime_dependency("github_api", ["~> 0.12"])
   spec.add_runtime_dependency("colorize", ["~> 0.7"])
   spec.add_runtime_dependency("overcommit", "~>0.31")
+  spec.add_runtime_dependency("rubocop", "~>0.31")
+  spec.add_runtime_dependency("rspec", "~>3.2")
 end