add parameter "page_metric" in confing.yml
change handling Volume#page_per_kbyte
review-vol: add --yaml option
page_metric in config.yml allows Array as arguments of PageMetric.new
sample.yml: add comments for catalogfile
Merge branch 'master' into fix-page_metric

Conflicts:
	doc/sample.yml
Merge pull request #364 from kmuto/fix-page_metric

add page_metric in config.yml, add --yaml option in review-vol