update self-dependency, move to es format

package.json

@@ -54,7 +54,7 @@
     "mocha": "^2.5.3",
     "remap-istanbul": "^0.6.4",
     "require-relative": "^0.8.7",
-    "rollup": "^0.31.2",
+    "rollup": "^0.32.0",
     "rollup-plugin-buble": "^0.11.0",
     "rollup-plugin-commonjs": "^3.0.0",
     "rollup-plugin-json": "^2.0.0",

rollup.config.js

@@ -42,6 +42,6 @@ export default {
 	moduleName: 'rollup',
 	targets: [
 		{ dest: 'dist/rollup.js', format: 'cjs' },
-		{ dest: 'dist/rollup.es.js', format: 'es6' }
+		{ dest: 'dist/rollup.es.js', format: 'es' }
 	]
 };