don't just mark gps fixes as sent, delete them. Also added some German strings

mobile/com.sap.sailing.android.tracking.app/res/values-de/strings.xml

@@ -18,5 +18,11 @@
     <string name="tracker_stopped">SAP Sailing Tracker gestoppt</string>
     <string name="scan_race_barcode">Scan Race Barcode</string>
     <string name="gps_fix_interval">GPS Fix Interval</string>
+    <string name="title_activity_regatta">Regatta</string>
+    <string name="title_activity_start">GPS Tracker gestartetp</string>
+    <string name="hello_world">Hello wörld!</string>
+    <string name="action_settings">Einstellungen</string>
+    <string name="please_confirm">Bitte bestätigen</string>
+    <string name="do_you_really_want_to_stop_tracking">Soll das Tracking wirklich beendet werden?</string>
 
 </resources>