Ak offers model

- Added offer model
- Added offers controller, show, and index page
- Added a description, name, sale price, actual price, and image to each offer


Storing currency information in a database can be tricky. When specifying a decimal you'll want to specify the precision and scale. See http://millarian.com/programming/ruby-on-rails/precision-and-scale-for-ruby-on-rails-migrations/ for more details.

Another common option is to store values as integers and convert them to decimal when needed.

Lastly, there is a popular gem for handling money values called [`money`](https://github.com/RubyMoney/money) and [`money-rails`](https://github.com/RubyMoney/money-rails) that you may want to look into.