2048 runtime packaged for PLAYCHIVE

Upstream repository: https://github.com/gabrielecirulli/2048
Pinned revision: 478b6ec346e3787f589e4af751378d06ded4cbbc
Upstream project: https://gabrielecirulli.github.io/2048/

2048 is licensed under MIT. The full upstream license is included at
2048-MIT.txt. The corresponding source is available from the repository above;
PLAYCHIVE's packaging script is scripts/build-2048-web.sh.

The package keeps all upstream HTML, JavaScript, Clear Sans webfonts and mobile
swipe input local. External promotional/store links in the upstream footer were
removed; score and game state stay in browser local storage.