Publisher not publishing derived events for classes, fixes #1558
Removed SubscribePlainMessages as it is not required
fixed json serializer issue

Conflicts:
	src/NServiceBus.Core.Tests/Serializers/Json/JsonMessageSerializerTest.cs
Merge pull request #1562 from Particular/Issue_1558

Issue 1558
Merge remote-tracking branch 'origin/hotfix-4.0.5'