Add foundation css framework + minimal setup
Add simple application layout
Improve basic layout

* Add main and aside content zones
* Extract width values from html to css
Improve look & feel
DRY specs with helpers, improve look & feel
Clean db after each test with database_cleaner
Implement new feature "Browsing by tags"

* WIP: ugly/spaghetti code, needs refactoring !
* WIP: tags should have a many-to many relationship with characteristics