DATACMNS-102 - Polishing.

Changed RepositoryConfiguration to return Streamable over Iterable. A couple of code reorganizations, suppression of raw type. Turned abstract helper classes into interfaces where possible. A couple of typos in JavaDoc.

Original pull request: #222.

src/test/java/org/springframework/data/repository/core/support/RepositoryCompositionUnitTests.java

@@ -39,17 +39,18 @@ import org.springframework.util.ReflectionUtils;
  * Unit tests for {@link RepositoryComposition}.
  *
  * @author Mark Paluch
+ * @author Oliver Gierke
  */
 @RunWith(MockitoJUnitRunner.class)
 public class RepositoryCompositionUnitTests {
 
 	@Mock QueryByExampleExecutor<Person> queryByExampleExecutor;
-
 	@Mock PersonRepository backingRepo;
 
 	RepositoryComposition repositoryComposition;
 
 	@Before
+	@SuppressWarnings("rawtypes")
 	public void before() {
 
 		RepositoryInformation repositoryInformation = new DefaultRepositoryInformation(