0.4.0

Bug fixes

• Fixed typo in error for case when failed to get bucket_id
• Fixed select by part of sharding key equal. Before this patch
  selecting by equality of partially specified multipart primary index
  value was misinterpreted as a selecting by fully specified key value.
• Fixed iteration with pairs through empty space returned nil.

Features

• truncate operation
• iterator returned by pairs is compatible with luafun