Use Unforwardable.modules, not Unforwardable.unforwardable.
Added ASIR::AdaptiveValue for use in RetryBehavior and worker graceful restart.
Use AdaptiveValue for retry time control.
with_retry must reset AdaptiveValue.
ASIR::AdaptiveValue: refactor ASIR::RetryBehavior sleep values.
Added AdaptiveValue#to_i, #to_f.