DATAREST-1499, DATAREST-1500 - Cleanups.

Moved off Spring Framework deprecations for HttpMessageNotReadableException. This required some rearrangements of method signatures for types (hopefully) exclusively used by internal abstractions (some public, but not very friendly for user extension in the first place).

Switched to consistent use of Pageable.unpaged() instead of null. Switched to the use of new factory methods in Spring HATEOAS. Some Java 8 based improvements in request handling to simplify the implementation code. Deprecation of code that got obsolete due to the use of the factory methods.

Moved off some deprecations in Jackson APIs.

Removed a couple of unused imports. General avoidance of common warnings. Suppression where needed. Removed dead code in configuration.

spring-data-rest-core/src/test/java/org/springframework/data/rest/core/domain/OrderRepository.java

@@ -30,7 +30,8 @@ public interface OrderRepository extends CrudRepository<Order, UUID> {
 	 * @see org.springframework.data.repository.CrudRepository#save(java.lang.Object)
 	 */
 	@Override
-	<S extends Order> S save(S entity);
+	@SuppressWarnings("unchecked")
+	Order save(Order entity);
 
 	/*
 	 * (non-Javadoc)

spring-data-rest-core/src/test/java/org/springframework/data/rest/core/mapping/RepositoryMethodResourceMappingUnitTests.java

@@ -113,7 +113,6 @@ public class RepositoryMethodResourceMappingUnitTests {
 	}
 
 	@Test // DATAREST-467
-	@SuppressWarnings("rawtypes")
 	public void returnsDomainTypeAsProjectionSourceType() throws Exception {
 
 		Method method = PersonRepository.class.getMethod("findByLastname", String.class);