v0.2.0

= New feature

- *Package pruning*

  You can remove old packages by `mamiya prune NUM`.
  It keeps last NUM packages.

= Enhancement

- *Specify application name via environment variable*

  You can use `$MAMIYA_APP` or `$MAMIYA_APPLICATION` to specify
  application name instead of `-a` (`--application`) in command line.

= Bug fixes

- agent status' .releases didn't get update incrementally.