added Underscore JS
added cart resource
added cart controller
added refactored download code, underscore template
documented download code
avoided zombie links and implemented cart controller
Merge pull request #1 from PirosB3/mine

Merged Daniels 'Mine' into Mathildas 'download' branch
committing new homepage images and CSS changes to devise views
committing changes to CSS and importing new photographs
merge
Added the shopping cart
Added form in print/download dropdown menu so can add shipping address in print payment form
Trying to add popups
Added payment images, post and packaging, popup to trash_icon
Changes
refactored cart, added helper method get_cart
added a bit more commenting
added stripe customer ID to user
added changes to checkout model. added default sent to false
added checkout_magazines, added relations, fixed some small bugs