Revert "Merge pull request #8 from 1syo/logger"

This reverts commit 6430b4667869d96e529a70a9def4a10235f527ae, reversing
changes made to f139210f1faa50303d0085e44b96f5c3404a6820.
Merge pull request #10 from 1syo/revert-pull-request-8

Revert "Merge pull request #8 from 1syo/logger"