Added metadatatest

I choose to not test getOrCreateMetadata method as this method is not used and should be removed. These repository tests are not thorough as the all use the same abstract class and has few individual methods.

src/test/java/NTNU/IDATT1002/repository/ImageRepositoryTest.java

@@ -15,6 +15,9 @@ import org.junit.jupiter.api.TestTemplate;
 
 /**
  * Test for {@link ImageRepository}
+ *
+ * @author madslun
+ * @version 1.0 13.04.20
  */
 class ImageRepositoryTest {