Wait for http endpoint to deliver certain payload

**User story**
As a citrus test developer, I want to be able to wait for a certain payload from my microservice http endpoint, to evaluate whether the service is ready or not.

**Additional context**
Let's say a microservice has a `/status` endpoint responding with a json document as follows:
```json
{ "status": "busy/ready/booting }
```
It would be great if one could state something like
```java
waitFor()
.http()
.url("http://myAwesomeService:8080/status")
.method(HttpMethod.GET)
.status(HttpStatus.OK)
.validate("$.status", "ready")
```

Start by tracing the existing waitFor().http() entry point and its handling of URL, method, and status assertions. Determine where response payload validation belongs, then verify that a JSON status value such as "ready" can be matched before considering the work complete; no files or tests are named in the issue.

Written by the indexing model from the issue text.