Remove mock server from servers list on destroy

lib/fog/digitalocean/requests/compute/destroy_server.rb

@@ -25,6 +25,9 @@ module Fog
             "event_id" => Fog::Mock.random_numbers(1).to_i,
             "status" => "OK"
           }
+
+          server = self.data[:servers].reject! { |s| s['id'] == id }
+
           response
         end
 

tests/digitalocean/requests/compute/destroy_server_tests.rb

@@ -7,6 +7,7 @@ Shindo.tests('Fog::Compute[:digitalocean] | destroy_server request', ['digitaloc
 
     test('#destroy_server') do
       service.destroy_server(server.id).body['status'] == 'OK'
+      service.servers.get(server.id) == nil
     end
 
   end