Previously the reconstructor would quarantine isolated durable
fragments that were more than reclaim_age old. This patch adds a
quarantine_age option for the reconstructor which defaults to
reclaim_age but can be used to configure the age that a fragment must
reach before quarantining.
Change-Id: I867f3ea0cf60620c576da0c1f2c65cec2cf19aa0
2fd5b87dc5