Create binstubs in vendor/bin.

You have to install rbenv-binstubs plugin to use them.
See http://qiita.com/naoty_k/items/9000280b3c3a0e74a618 for more information.
Add db/schema.rb to .gitignore.
Merge pull request #45 from a1125ts/db_schema

db/schema.rbを.gitignoreに追加しました．