Added interfaces for Grouper and Aggregator

java/com.sap.sailing.datamining/src/com/sap/sailing/datamining/Aggregator.java

@@ -0,0 +1,9 @@
+package com.sap.sailing.datamining;
+
+import java.util.Collection;
+
+public interface Aggregator {
+    
+    public double aggregate(Collection<GPSFixWithContext> data);
+
+}

java/com.sap.sailing.datamining/src/com/sap/sailing/datamining/Grouper.java

@@ -0,0 +1,10 @@
+package com.sap.sailing.datamining;
+
+import java.util.Collection;
+import java.util.Map;
+
+public interface Grouper<K> {
+
+    public Map<K, Collection<GPSFixWithContext>> group(Collection<GPSFixWithContext> data);
+    
+}