INT-2856:Add support for adding/removing individual recipients to the Re...

Add support for adding/removing individual recipients to the RecipientListRouter
Actually it is a bad doc: you shouldn't say about all methods, just mention `RecipientListRouterManagement` is enough. But you have to show in docs some sample on the matter. 
And, of course, it is an important to say from which **version** it has been introduced.
Anyway you didn't say something that now  `RecipientListRouter` can be configured without `Recipients` for feature reconfiguration at runtime.
BTW, you can adapt here the Oleg's comment from JIRA