Fixed API types to Any, instead of AnyRef

Signed-off-by: Tsuyoshi Ozawa <ozawa.tsuyoshi@gmail.com>
Bump version 0.3.0

This version supports:
  * Scala object serialization/deseliazation.

NOTE: In this version, Scala 2.8.x is deprecated, and 2.10.x is not yet
supported, because of msgpack dependency. Supporting these versions is TODO.

Signed-off-by: Tsuyoshi Ozawa <ozawa.tsuyoshi@gmail.com>