Zone check

1) Print store name in the error log so it is easy to identify the store.
2) Ignore the zone id in the proximity list if the zone is same as the current zone. Client operations will fail explicitly instead of silently failing. The check can be made better , it should be post condition but not comfortable with changing the code, just added minor checks that is safe.
3) Refactored the copy pasted code into its own method.
4) Modified the proximityList from LinkedList to ArrayList. The major operation is get and ArrayList will perform better in all cases. Abstracted the type and returning List so can be changed in the future if we want it.