feat(packaging): automatically copy LICENSE to dist folders

tools/build/multicopy.js

@@ -0,0 +1,26 @@
+/**
+ * A utility that allows copying one file to multiple directories, such
+ * as the LICENSE file.
+ */
+var path = require('path');
+var fs = require('fs');
+
+module.exports = function(gulp, plugins, config) {
+  return function() {
+    var content = fs.readFileSync(config.src);
+    getSubdirs(config.dest).forEach(function(subDir) {
+      var destFile = path.join(config.dest, subDir, path.basename(config.src));
+      fs.writeFileSync(destFile, content);
+    });
+  };
+};
+
+function getSubdirs(rootDir) {
+  return fs.readdirSync(rootDir).filter(function(file) {
+    if (file[0] === '.') {
+      return false;
+    }
+    var dirPath = path.join(rootDir, file);
+    return fs.statSync(dirPath).isDirectory();
+  });
+}