refacter code comment
Festival#sortで新しい順にフェスを取得できる #176
refactor spec #176
fix typo#176
place festivals in order of newer start-date
spec for Festival#finished?
refactor code (move Festival's validates upon methods definitions)
check finished fes by Festival#finished?
use Date instead DateTime
weaken finished fes
Merge branch 'master' into weaken-finished-fes
Merge pull request #176 from i-d-e-a-t/weaken-finished-fes

Weaken finished Fes       ε≡≡ﾍ( ´Д`)ﾉ      master