Gem will_pageinate 分页插件的问题
will_paginate分页时怎么控制分页显示的页数，这个默认的是 12 个。太大了，哪里可改小点
https://github.com/mislav/will_paginate/blob/master/lib/will_paginate/view_helpers.rb
<%= will_paginate @posts, inner_window: 2 %>
默认情况下是 4
:inner_window => 4, # links around the current page
