Updated license to use SPDX identifier.

Author: danbell

package.json

@@ -37,7 +37,7 @@
  "build-standalone": "browserify -s ModuleTranspiler -e lib/index.js -o es6-module-transpiler.js"
  },
  "author": "Square, Inc.",
- "license": "Apache 2",
+ "license": "Apache-2.0",
  "dependencies": {
  "ast-util": "^0.5.1",
  "esprima-fb": "^7001.1.0-dev-harmony-fb",
@@ -56,4 +56,4 @@
  "fs": "./lib/browser/fs.js",
  "./lib/index.js": "./lib/browser/index.js"
  }
-}
+}