change application layout
Browsing Categories

* create the category model and migrations
* create the region show page

Category Creation

* create category controller
* add category routes
* update regions controller
* update regions views
Add Posts

* generate posts migration and model (belongs_to region)
* posts resource nested under regions in config/routes
* create posts_controller
* make posts#show view that renders a _post partial
Users can add posts

* migrate new table for posts with region_id, category_id and user_id
* posts routes resource nested under categories
* make posts controller
* create views for posts#show, posts#edit, posts#new
* _form partial extracted for posts#edit and posts#new
* _errors partial extracted for application