added a test for ReVIEW::Book#{part,each_part}
added a test for ReVIEW::Book#{part,each_part}

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