add gem: carrierwave (image uploader)
create image_uploader.rb, add public/uploads to .gitignore
mount uploader, change attachment from text_field to file_field
change views to show the attachment using Carrierwave's conventions
change views to show the attachment using Carrierwave's conventions
add gem: RMagick
add RMagick methods to resize images
add gem: figaro
generate application.yml via figaro