Added an option to use Rest Assured version 3.0

without this change it's impossible to use Rest Assured 3.0 with Spring Cloud Contract. That's because we are adding Rest Assured 2.0 imports.
with this change we detect Rest Assured version. If 3.0 is available on the classpath we change the imports

fixes #266

samples/standalone/messaging/stream-source/src/test/java/com/example/source/SensorSourceTestBase.java

@@ -16,11 +16,14 @@
 
 package com.example.source;
 
+import io.restassured.module.mockmvc.RestAssuredMockMvc;
+import org.junit.Before;
 import org.junit.runner.RunWith;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.cloud.contract.verifier.messaging.boot.AutoConfigureMessageVerifier;
 import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;
+import org.springframework.web.context.WebApplicationContext;
 
 /**
  * Base class for sensor autogenerated tests (used by Spring Cloud Contract).
@@ -37,6 +40,14 @@ public abstract class SensorSourceTestBase {
 	@Autowired
 	ContractVerifierSampleStreamSourceApplication application;
 
+	@Autowired
+	WebApplicationContext context;
+
+	@Before
+	public void setup() {
+		RestAssuredMockMvc.webAppContextSetup(this.context);
+	}
+
 	public void createSensorData() {
 		application.poll();
 	}

samples/standalone/messaging/stream-source/src/test/resources/contracts/shouldReturnOkWhenServiceIsHealthy.groovy

@@ -0,0 +1,11 @@
+package contracts
+
+org.springframework.cloud.contract.spec.Contract.make {
+	request {
+		method(GET())
+		url("/health")
+	}
+	response {
+		status(200)
+	}
+}