Rubocop doesn't support Ruby 1.9 anymore

Author: rafaelfranca

Gemfile

@@ -25,7 +25,7 @@ group :test do
   gem 'mime-types', '~> 1.25', :platforms => [:jruby, :ruby_18]
   gem 'rspec', '>= 3'
   gem 'rspec-mocks', '>= 3'
-  gem 'rubocop', '>= 0.19', :platforms => [:ruby_19, :ruby_20, :ruby_21]
+  gem 'rubocop', '>= 0.19', :platforms => [:ruby_20, :ruby_21]
   gem 'simplecov', '>= 0.9'
   gem 'rest-client', '~> 1.6.0', :platforms => [:jruby, :ruby_18]
 end