set links list by order of number of upvotes
write method for sorting links according to date submitted at tally
add comment form to link show page
show comments on link show page
add association comment belongs to commentable
add association comment has many comments
add association link has many comments, as commentable
add header image
replace grainy header image with fresh one
pass our first Capybara test
add reply buttons to comments
readjust spacing for buttons
add reply partial view to comment