Chaining of matchers and stub_method calls

Avoids repeating same subject for multiple expectations:

```objc
request.headers should
    contain(@"Authorization: key"),
    contain(@"X-Request-Id: id");
```

and similarly for stub_method; however, calls are not separated by commas since stub_method macro already starts with one:

```objc
service 
    stub_method("get").and_return(200)
    stub_method("post").and_return(201);
```