Docker build fails

Building with docker fails with:

```
===== RUNNING: cabal_install --ghcjs ./codeworld-prediction ./codeworld-error-sanitizer ./codeworld-api ./codeworld-base ./codeworld-game-api ./codeworld-available-pkgs
Warning: the --global flag is deprecated -- it is generally considered a bad
idea to install packages into the global store
Resolving dependencies...
cabal: Could not resolve dependencies:
[__0] trying: codeworld-available-pkgs-0.1.0.0 (user goal)
[__1] unknown package: prob (dependency of codeworld-available-pkgs)
[__1] fail (backjumping, conflict set: codeworld-available-pkgs, prob)
After searching the rest of the dependency tree exhaustively, these were the
goals I've had most trouble fulfilling: codeworld-available-pkgs, prob

========== Aborting: Command failed. ==========
DIRECTORY: .
COMMAND : cabal_install --ghcjs ./codeworld-prediction ./codeworld-error-sanitizer ./codeworld-api ./codeworld-base ./codeworld-game-api ./codeworld-available-pkgs
EXIT CODE: 1
===============================================
```