Added endpoint to check out

Use buys item, records added to 'purchases' table and cart is cleared
Added paragraph styling for when the user checks out
Changed button to link to user page, added confirmation message

Text now changes to "Boom! Added!" when you add an item to your cart
CSS3 transition
Fixed hover style on btn-submit
Added integration with Stripe for payments

Specifically using the super-simple Stripe Checkout for payments
Added 'list item' nav bar item

Also removed the 'HOME' item
Added Stripe Checkout JS API and List Item JS
Logo for the Stripe popup
Overlay to list item

Needs styling etc