1.在Gemfile中增加 gem 'bootstrap-sass', '~> 3.3.5.1'
2.bundle install
3.把assets/stylesheets/application.css重命名为application.css.scss
4.在这个文件中增加:
@import "bootstrap-sprockets";
@import "bootstrap";
5.在assets/javascriptsheets/application.js中增加://= require bootstrap-sprockets