[New] implemented a TransactionResult

This allows reflecting on actual changes performed by the transaction if
this is needed by the caller. One use case would be to perform observer
updates after a transaction was completed.

src/main/java/ch/eitchnet/xmlpers/api/ModificationResult.java

@@ -1,5 +1,6 @@
 package ch.eitchnet.xmlpers.api;
 
+import java.util.ArrayList;
 import java.util.List;
 
 public class ModificationResult {
@@ -9,6 +10,13 @@ public class ModificationResult {
 	private final List<?> updated;
 	private final List<?> deleted;
 
+	public ModificationResult(String key) {
+		this.key = key;
+		this.created = new ArrayList<>();
+		this.updated = new ArrayList<>();
+		this.deleted = new ArrayList<>();
+	}
+
 	public ModificationResult(String key, List<?> created, List<?> updated, List<?> deleted) {
 		this.key = key;
 		this.created = created;

src/main/java/ch/eitchnet/xmlpers/api/TransactionResult.java

@@ -108,13 +108,6 @@ public class TransactionResult {
 		this.closeDuration = closeDuration;
 	}
 
-	/**
-	 * @return the modificationByKey
-	 */
-	public Map<String, ModificationResult> getModificationByKey() {
-		return this.modificationByKey;
-	}
-
 	/**
 	 * @param modificationByKey
 	 *            the modificationByKey to set