add default_external: refs #75
add default_external: refs #75

suzuki/review,murashitas/review,kuad9/review_study,suzuki/review,murashitas/review,krororo/review,krororo/review,orangain/review,krororo/review,kmuto/review,kmuto/review,kmuto/review,takahashim/review,kuad9/review_study,takahashim/review,masawada/review,orangain/review,masawada/review