authencate_user! method support
user should login first to manage slides
update the link to upload slide page
slides resources extended with new and create actions
add bucket config
new model Slide
slides#new action, mainly generate up token and specify callback url
new slide upload form
route entrance to receive upload callback notification
placeholder will be used to process notification callbacks
insert a foreign key category_id to slides table
slides insert a new foreign key
create new model category
setup a belongs_to association from slide to category
data seed file to generate categories
update category links with real data
retrieve real category from database
update category show page
add new demo image and all pages use same one
new slide should select a category