Fix bugs in Carbonite sync and repair code.
Fix bugs in Carbonite sync and repair code.

Each node in Carbonite should only sync for objects in the
range it is directly responsible for; old code had the same
extravagance of syncing a too-large range, though that doesn't
really affect correctness.

Repairs were being generatd unnecessarily because code had been
neglecting to count copies that were stored locally.  Add
the local (live) tree to the trees counted.

weidezhang/dht,weidezhang/dht,sit/dht,sit/dht,sit/dht,weidezhang/dht,sit/dht,weidezhang/dht,sit/dht,weidezhang/dht