Builder new

This is an MVP for the artist level builder.

So far it allows someone to put blocks together and create an artist drawing. Then, that level is stored and a link is given to the user. Navigating to that link shows the level and students can try to solve it.

As of yet there's no functionality for instructions, required blocks etc. That's coming.

It uses a couple hacks including
- Creating special artist levels (in blockly) for creating a level and for displaying a custom level.
- A dummy script into which custom levels are added.