Integration with REST-assured

[aguibert]

Add integration with REST-assured if it's on the classpath. This will save the user from needing to write the following code:

RestAssured.baseURI = "http://" + app.getContainerIpAddress() + "/myservice";
RestAssured.basePath = "/myapp";
RestAssured.port = app.getFirstMappedPort();

RestAssured.config = RestAssured.config.objectMapperConfig(ObjectMapperConfig.objectMapperConfig()
                                    .defaultObjectMapperType(ObjectMapperType.JSONB));

This can't be merged yet because neither the ObjectMapperType.JSONB enum nor the objectMapper(ObjectMapperType) config methods exist yet, but I've proposed both to REST-assured in this PR: rest-assured/rest-assured#1257

[aguibert]

Fixes #130