Add "add to home screen" icons for shared items
 - Add flappy icon for flappy levels
 - Add code.org logo for other shareable levels
Remove unnecessary helper
Merge pull request #1084 from code-dot-org/flappy_home_screen_icon

Add "add to home screen" icons for shared items [finishes #75058538]
Include helper dependency
Merge pull request #1089 from code-dot-org/flappy_home_screen_icon

Fix undefined method `asset_url` on /sh/ pages
Automatically built
Merge pull request #1090 from code-dot-org/finished

Deploy to delivered