thrift: Send empty col metadata when describing ks
thrift: Send empty col metadata when describing ks

This patch ensures we always send the column metadata, even when the
column family is dynamic and the metadata is empty, as some clients
like cassandra-cli always assume its presence.

Signed-off-by: Duarte Nunes <a60e8b7496f7715d71354fe4c06dd24017025bf1@scylladb.com>
Message-Id: <1470740971-31169-1-git-send-email-a60e8b7496f7715d71354fe4c06dd24017025bf1@scylladb.com>

raphaelsc/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,scylladb/scylla,duarten/scylla,avikivity/scylla,duarten/scylla,avikivity/scylla,duarten/scylla,avikivity/scylla,raphaelsc/scylla,raphaelsc/scylla