Install scripts, build app with rollup & configurable mirror app id

ext/build.js

@@ -0,0 +1,20 @@
+const spawn = require('child_process').spawn;
+const argv = require('minimist')(process.argv.slice(2));
+
+const appId = argv.appId || "19A6F4AE";
+
+const child = spawn(
+    `webpack --env.appId=${appId} `
+        + '&& web-ext build '
+            + '--overwrite-dest '
+            + '--source-dir '
+            + '../dist/ext/unpacked '
+            + '--artifacts-dir '
+            + '../dist/ext '
+        + '&& mv ../dist/ext/*.zip ../dist/ext/ext.xpi'
+  , {
+        shell: true
+    }
+);
+child.stdout.pipe(process.stdout);
+child.stderr.pipe(process.stderr);