A user can view posts in a paginated list

* install Kaminari gem
* run bundle and the kaminari generator
* modify the generated config/initializers
* modify post model to override default kaminari config
* modify categories controller to implement pagination
* modify category#show to implement pagination
It's preferable to use parenthesis around params[:page] here. The general rule is to use parens when doing assignment. So:

```ruby
@posts = @category.posts.page(params[:page])
```