Use correct redis logger level in workers

Signed-off-by: Dmitriy Kalinin <dmitriy@pivotallabs.com>
allow Bosh::Retryable to accept custom error matchers

Signed-off-by: Dmitriy Kalinin <dmitriy@pivotallabs.com>
retry creating/deleting AWS instance if "The service is unavailable" error is returned

Signed-off-by: Dmitriy Kalinin <dmitriy@pivotallabs.com>