Merge pull request pfnet#152 from pfnet/update-to-v0.3.0

Update to v0.3.0

Merge pull request pfnet#114 from pfnet/muupan-patch-1

Update the version to v0.2.1

Merge pull request pfnet#109 from pfnet/muupan-patch-1

Update the version in setup.py to 0.2.0

Make update_counter multiprocess safe (pfnet#30)