Camel result

Prerequisite: https://github.com/Activiti/Activiti/pull/400

It was not possible to return something from activiti to camel.
With this patch it is possible to return value by inserting values into "camelResult" variable which is a hashmap.
All the key/value pairs are copied back as camel property except the one with key equal to "camelBody" which will be considered as exchange payload.
The code is not backward compatible. Previously created instance Id was returned both as a property and as camel body. I don't see any reason to return it as camel Body.
Alghoug  it is possible to define the behavior so that if no object with key equal to "camelBody" is put in the "camelResul" then return the process intance ID as body. Then  it would be backward compatible, but still not very logical.