Merge pull request #7 from kylefdoherty/emily

Emily
Merge pull request #8 from kylefdoherty/emily

fixes new user order creation, updates todo, adds slash to login url in ...
Merge pull request #9 from kylefdoherty/emily

adds cart to nav, order history to user show, and buy button to sellers ...
added quantity to products
Merge pull request #10 from kylefdoherty/emily

link to edit user from show page, add product link in seller partial
added quantity to product show page, to line_item table, changed order total method to use li total for grand total, added continue shopping link
changed orders table on user show page to use li quantity and total to use li total
Merge pull request #11 from kylefdoherty/quantity

Quantity
purchased items decrement the quantity for that item after checkout
fixes merge conflicts