Add maze builder functionality.
add solutions for the rest of stage2/maze
solutions for stage 9 (karel levels)
stage 13 solutions
tests for stage 7 (artist)
Inline Cairo/node-canvas instructions

This has been a common stumbling point and general annoyance during setup. Moving the prerequisite note above install instructions.
Fix path for build dir.
Merge pull request #461 from code-dot-org/levelTests

Add a bunch more test solutions
add simple move blocks, clean up turtle movement logic a bit
[Finishes 68301834] Pong -> Bounce
[Finishes 68245530]: text change
[Finishes 68301870]: hideShowCode changes
[Finishes 68245434]: remove ideal block count
Built Results
[Finishes 68301870]: PR feedback + use enableShowCode for feedback dialog as well
Merge pull request #462 from code-dot-org/pivotal_68245434_68301870

Pivotal 68245434 68301870
Pong -> Bounce
Set explicit start positions for stage 11 puzzle 3 and stage 11 puzzle 4
Merge pull request #463 from code-dot-org/pivotal_68328010

Set explicit start positions for stage 11 puzzle 3 and stage 11 puzzle 4
Update README.md