Move Gruntfile off of coffescript.

Gruntfile.js

@@ -0,0 +1,70 @@
+/*
+ * decaffeinate suggestions:
+ * DS102: Remove unnecessary code created because of implicit returns
+ * Full docs:
+ * https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
+ */
+module.exports = function(grunt) {
+  grunt.initConfig({
+    build: {client: 'src/**/*.js'},
+
+    // JSHint options
+    // http://www.jshint.com/options/
+    jshint: {
+      plugin: {
+        files: {src: 'lib/**/*.js'},
+        options: {
+          // node
+          node: true,
+          strict: false
+        }
+      },
+      options: {
+        quotmark: 'single',
+        bitwise: true,
+        indent: 2,
+        camelcase: true,
+        strict: true,
+        trailing: true,
+        curly: true,
+        eqeqeq: true,
+        immed: true,
+        latedef: true,
+        newcap: true,
+        noempty: true,
+        unused: true,
+        noarg: true,
+        sub: true,
+        undef: true,
+        maxdepth: 4,
+        maxlen: 100,
+        globals: {}
+      }
+    },
+
+    simplemocha: {
+      options: {ui: 'bdd', reporter: 'dot'},
+      unit: {src: ['test/**/*.spec.js']}
+    },
+
+    'npm-contributors':
+        {options: {commitMessage: 'chore: update contributors'}},
+
+    bump: {
+      options: {commitMessage: 'chore: release v%VERSION%', pushTo: 'upstream'}
+    }
+  });
+
+  grunt.loadNpmTasks('grunt-auto-release');
+  grunt.loadNpmTasks('grunt-contrib-jshint');
+  grunt.loadNpmTasks('grunt-bump');
+  grunt.loadNpmTasks('grunt-npm');
+  grunt.loadNpmTasks('grunt-simple-mocha');
+
+  grunt.registerTask('default', ['jshint', 'test']);
+  grunt.registerTask('test', ['simplemocha:unit']);
+  return grunt.registerTask(
+      'release', 'Bump and publish to NPM.',
+      type => grunt.task.run(
+          ['npm-contributors', `bump:${type || 'patch'}`, 'npm-publish']));
+};