Update ProductAccountPosition.java
Position calculation from receipts, persistence of receipts, position snapshot: BETA VERSION
Merge remote-tracking branch 'origin/master'
Update ReceiptStorage.java
Position calculation from receipts, persistence of receipts, position snapshot.
PositionSnapshot not working.
Merge remote-tracking branch 'origin/master'

Conflicts:
	yats/src/main/java/org/yats/messagebus/messages/OrderCancelMsg.java
	yats/src/main/java/org/yats/trading/OrderNew.java
	yats/src/main/java/org/yats/trading/ReceiptStorage.java
	yats/src/test/java/org/yats/trading/ReceiptStorageTest.java
Position calculation from receipts, persistence of receipts, position snapshot.
PositionSnapshot not working.
Merge remote-tracking branch 'origin/master'

Conflicts:
	yats/src/main/java/org/yats/trading/ReceiptStorage.java
	yats/src/test/java/org/yats/trading/ReceiptStorageTest.java
Position calculation from receipts, persistence of receipts, position snapshot.
PositionSnapshot not working.