Merge pull request #3 from ksurent/master

Fixed minor typos in error messages
solved cleanup bug with handle_expired_items
version 0.15
added peek_item()
version 0.16
bugfix for MaxItems (dont use chunk size for counting)
Merge pull request #4 from ksurent/master

Make ClaimFIFO::Item interface more like ReliableFIFO::Item
version 0.17