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
The number of spaces used for indentation are inconsistent here from the rest of your project. I blame Kaminari, but no reason not to fix them. It should be 2 spaces instead of 3.