Transition to GitHub Actions (#136)

* gulpfile.js: fix ESLint warnings

* package.json: add shortcut scripts

* scripts/games: do a shallow git clone to save time

* ci: migrate to GitHub Actions

scripts/games/app.js

@@ -38,7 +38,7 @@ function gitPull(directory, repository) {
   } else {
     logger.info(`Cloning repository from Github : ${directory}`);
     logger.info(`git clone ${repository}`);
-    exec(`git clone ${repository}`);
+    exec(`git clone --depth=1 ${repository}`);
   }
 }