[ec2] small fixes for mock inconsistencies

lib/fog/aws/requests/ec2/attach_volume.rb

@@ -49,7 +49,7 @@ module Fog
                 'status'      => 'attaching',
                 'volumeId'    => volume_id
               }
-              volume['attachmentSet'] << data
+              volume['attachmentSet'] = [data]
               response.status = 200
               response.body = {
                 'requestId' => Fog::AWS::Mock.request_id

lib/fog/aws/requests/ec2/describe_instances.rb

@@ -80,11 +80,14 @@ module Fog
             when 'rebooting'
               instance['instanceState'] = { 'code' => 16, 'name' => 'running' }
             when 'shutting-down'
-              if Time.now - @data[:deleted_at][instance['instanceId']] > 2
+              if Time.now - @data[:deleted_at][instance['instanceId']] > 1
                 instance['instanceState'] = { 'code' => 16, 'name' => 'terminating' }
+              elsif Time.now - @data[:deleted_at][instance['instanceId']] > 2
+                @data[:deleted_at].delete(instance['instanceId'])
+                @data[:instances].delete(instance['instanceId'])
               end
             when 'terminating'
-              if Time.now - @data[:deleted_at][instance['instanceId']] > 4
+              if Time.now - @data[:deleted_at][instance['instanceId']] > 1
                 @data[:deleted_at].delete(instance['instanceId'])
                 @data[:instances].delete(instance['instanceId'])
               end