Removed unused models, refactored associations and more...

![](http://static2.fjcdn.com/thumbnails/comments/Quick+Burn+them+before+they+lay+eggs+_bb7777e5a17e4c37763e9a2069da4ad5.gif)

:warning: **HOT CHANGES** :warning: 

- Removed all the models that we're not using right now for the first beta (Product, Order, etc.)
- Removed all the related migrations
- Renamed `Customer` model to a more appropriate `Group`
- Removed `Membership` model and split it in more scoped membership models (a lot of conditions == code smell)
- Upgraded RSpec to 2.14

I'm sorry for this messy-one-ugly-commit PR...