Add onPrepareRef option to Multicast, Splitter and Recipient List EIPs which is new in Camel 2.8

Camel 2.8 introduces a new onPrepareRef attribute you can set on the following 3 eips:

• multicast
• recipient list
• splitter

Its a Processor which allows end user to do any custom logic before the exchange is being processed. For example in the multicast case and you use mutable message bodies, then you can deep clone those, so changes are not visible between the multicasted messages. Alternative end users can enrich the message before they are processed etc.