Since calculate_pending_ranges will modify token_metadata, we need to
replicate to other shards. With this patch, when we call
calculate_pending_ranges, token_metadata will be replciated to other
non-zero shards.
In addition, it is not useful as a standalone class. We can merge it
into the storage_service. Kill one singleton class.
Fixes#1033
Refs #962
Message-Id: <fb5b26311cafa4d315eb9e72d823c5ade2ab4bda.1457943074.git.asias@scylladb.com>
(cherry picked from commit 9f64c36a08)