Mention arangodump/arangorestore in CHANGELOG for 2.1.
arangorestore/cluster: default to 1 shard.

If shards is not given in the structure description, take 1 shard.
Silence a compiler warning about signedness.
Add a ClusterMethod to truncate a collection in a cluster.
If a collection cannot be dropped during restore, truncate it.
Add documentation for cluster dump/restore.
Fix restore documentation for cluster.