added redis-namespace to Gemfile for CI

Gemfile

@@ -2,6 +2,7 @@ source 'https://rubygems.org'
 
 group :test do
   gem "rspec", "~> 3.0.0.beta1"
+  gem "redis-namespace", "~> 1.4.1"
 end
 
 # Specify your gem's dependencies in weixin_authorize.gemspec