Add pcntl extension to Composer requirement
Logging honour verbose level
Use LOG LEVEL constant
Update Changelog and version bump
Drop php extension

Delegate logging to Worker::log()
Append ISO 8601 formatted date to all log entries
log starting event inside Worker class
Drop support if igbinary serializer
Update changelog
Update Composer dependencies
Fix composer
Move fresque dependency to suggestion
Fix trailing comma
merge
merge
redis lost connection 対応