Remove old pins only required for ruby 1.8 support

Author: deivid-rodriguez

Gemfile

@@ -16,8 +16,6 @@ end
 group :test do
   gem "childlabor"
   gem "coveralls", ">= 0.8.19"
-  gem "mime-types", "~> 1.25", :platforms => [:jruby]
-  gem "rest-client", "~> 1.6.0", :platforms => [:jruby]
   gem "rspec", ">= 3"
   gem "rspec-mocks", ">= 3"
   gem "rubocop", ">= 0.19"