Replace Hash#except with Hash#slice.

Since Hash#except is not in standard Ruby and Vagrant removed active_support i18n that provides the polyfill in Vagrant 2.2.7; even the polyfill was just Hash#slice minus the requested keys. Seemed simpler to inline than monkey-patch Hash...

Resolves mitchellh#566

Based on mitchellh#575

lib/vagrant-aws/action/connect_aws.rb

@@ -38,7 +38,7 @@ def call(env)
 
           @logger.info("Connecting to AWS...")
           env[:aws_compute] = Fog::Compute.new(fog_config)
-          env[:aws_elb]     = Fog::AWS::ELB.new(fog_config.except(:provider, :endpoint))
+          env[:aws_elb]     = Fog::AWS::ELB.new(fog_config.slice(*fog_config.keys - [:provider, :endpoint]))
 
           @app.call(env)
         end