make input/output operation types being plug-able in automation

In automation client and server, we need a way for plugging new types of input/output. This will be achieved by contributing custom POJO marshallers in client and server framework.

Marshallers will be referenced in json content by using a type name. A typical input content will be :

{"input":"myobject:

{\"message\": \"hello world\"}

","params":{},"context":{}}

and output content :
{
"entity-type": "myobject",
"message": "hello world"
}

Also, we want to be able to use references instead of inline content in input.