Fix bundler args in travis.

Author: gkellogg

Gemfile

@@ -10,6 +10,6 @@ group :debug do
 end
 
 group :development, :test do
-  gem 'simplecov',  require: false, platform: :mri
-  gem 'coveralls',  require: false, platform: :mri
+  gem 'simplecov',  platforms: :mri
+  gem 'coveralls',  '~> 0.8', platforms: :mri
 end