update utile.User as Google User API interface

https://github.com/mback2k/appengine-oauth-profile/blob/master/handlers/userinfo.py
add utils.login_required
Merge branch 'login_required'
Merge remote-tracking branch 'tap/master' into #14
add model.User
refactor
fix
Merge remote-tracking branch 'tap/master' into #14
ひと通りのModelを定義した
indexを最適化した