chore(build): create changelogs each release

fixes #158

package.json

@@ -39,6 +39,7 @@
     "grunt": "^0.4.5",
     "grunt-cli": "^0.1.13",
     "grunt-contrib-jshint": "^0.10.0",
+    "grunt-conventional-changelog": "^1.1.0",
     "grunt-copyright": "^0.1.0",
     "grunt-jscs": "^0.7.1",
     "grunt-mocha-test": "^0.12.0",
@@ -47,8 +48,8 @@
     "insist": "0.x",
     "jshint-stylish": "^1.0.0",
     "jwcrypto": "^0.5.0",
-    "mocha-text-cov": "^0.1.0",
     "load-grunt-tasks": "^0.6.0",
+    "mocha-text-cov": "^0.1.0",
     "nock": "^0.48.0",
     "read": "^1.0.5",
     "time-grunt": "^1.0.0"

tasks/release.js

@@ -0,0 +1,15 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+module.exports = function (grunt) {
+  'use strict';
+
+  grunt.config('changelog', {
+    dest: 'CHANGELOG.md'
+  });
+
+  grunt.registerTask('release', [
+    'changelog'
+  ]);
+};