Add hamcrest-library to spring-boot's compile classpath

Fixes build break introduced in 31336c2.

spring-boot/pom.xml

@@ -159,6 +159,11 @@
 			<artifactId>undertow-servlet</artifactId>
 			<optional>true</optional>
 		</dependency>
+		<dependency>
+			<groupId>org.hamcrest</groupId>
+			<artifactId>hamcrest-library</artifactId>
+			<optional>true</optional>
+		</dependency>
 		<dependency>
 			<groupId>org.hibernate</groupId>
 			<artifactId>hibernate-entitymanager</artifactId>