Merge pull request #1315 from Turbo87/es6-parser

parser: Change suffix to use ES6 default module export

.istanbul.yml

@@ -1,2 +1,2 @@
 instrumentation:
-    excludes: ['**/spec/**']
+    excludes: ['**/spec/**', '**/handlebars/compiler/parser.js']

src/parser-prefix.js

@@ -1 +1 @@
-/* istanbul ignore next */
+// File ignored in coverage tests via setting in .istanbul.yml

src/parser-suffix.js

@@ -1,2 +1 @@
-exports.__esModule = true;
-exports['default'] = handlebars;
+export default handlebars;