Centralize npm installation in root, so you only have to do it once

install.js

@@ -0,0 +1,10 @@
+var fs = require("fs");
+var execSync = require("child_process").execSync;
+var path = require("path");
+
+fs.readdirSync("stages").forEach(function(stage) {
+  var cwd = path.join(__dirname, "stages", stage);
+
+  console.log("Installing packages for " + cwd);
+  execSync("elm-package install --yes", { cwd: cwd });
+});