added devise authentication and Users controller
added carrierwave. Mounted ImageUloader to :file column on Image class and updated form and show Image views
added user_id to image. updated Image create method so that @image = current_user.images.new(). Added user_id to image show view
scaffolded Mosaic
added Mosaic model. added join table images_mosaics. Mosaic.new = current_user.mosaics.new(). Mosaic new form allows collection_select from current_user's images.
added gem 'rails_12factor'
updated config/environments/production in order to deploy to Heroku