New web client expectation API

[vietj]

Documentation is updated with the HTTP response expectation API, response predicate API is deprecated.

[Fyro-Ing]

Hi

Now, with this solution, response body is decoded before expect test, with BodyCodec But when success body result is not same as error body result, there is DecodedException

webclient.post(xx)
.as(json(Integer.class)
.send()
.expecting(SC_SUCCESS)

ok body is "5"

error body is json as 
{
  code: mycode
  message: message
}