made mime-types compatible with both 1.8 and 1.9
made mime-types compatible with both 1.8 and 1.9

--HG--
branch : 2.1-ruby1.9

RubenVerborgh/nanoc,barraq/nanoc,hilohiro/nanoc,nanoc/nanoc,legallybrown/nanoc,gjtorikian/nanoc,remko/nanoc