Fix binary incompatibility of old TestRestTemplate

The TestRestTemplate is deprecated (so people can still use it)
but unusable because it only has constructors which depend on the
new options enum.

spring-boot-test/src/test/java/org/springframework/boot/test/TestRestTemplateTests.java

@@ -0,0 +1,15 @@
+package org.springframework.boot.test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.Test;
+
+public class TestRestTemplateTests {
+
+	@Test
+	public void canCreateTemplateFromOwnOptions() {
+		TestRestTemplate template = new TestRestTemplate(TestRestTemplate.HttpClientOption.ENABLE_REDIRECTS);
+		assertThat(template).isNotNull();
+	}
+
+}