add grunt clean to build

Gruntfile.js

@@ -102,7 +102,8 @@ module.exports = function(grunt) {
         src: ['mocha/mocha.css', 'mocha/mocha.js', 'chai/chai.js'],
         dest: 'test/lib/'
       }
-    }
+    },
+    clean: ['dist/']
   });
 
   // Load the plugin(s)
@@ -114,9 +115,10 @@ module.exports = function(grunt) {
   grunt.loadNpmTasks('grunt-jsdoc');
   grunt.loadNpmTasks('grunt-mocha-test');
   grunt.loadNpmTasks('grunt-contrib-copy');
+  grunt.loadNpmTasks('grunt-contrib-clean');
 
   grunt.registerTask('default', 'Build OpenPGP.js', function() {
-    grunt.task.run(['browserify', 'replace', 'uglify', 'npm_pack']);
+    grunt.task.run(['clean', 'browserify', 'replace', 'uglify', 'npm_pack']);
     //TODO jshint is not run because of too many discovered issues, once these are addressed it should autorun
     grunt.log.ok('Before Submitting a Pull Request please also run `grunt jshint`.');
   });

package.json

@@ -6,14 +6,21 @@
   "engines": {
     "node": ">=0.8"
   },
-  "keywords": ["crypto", "pgp", "gpg", "openpgp"],
+  "keywords": [
+    "crypto",
+    "pgp",
+    "gpg",
+    "openpgp"
+  ],
   "main": "src/index.js",
   "directories": {
     "lib": "src"
   },
   "files": [
     "src/",
-    "test/unittests.js", "test/general", "test/crypto"
+    "test/unittests.js",
+    "test/general",
+    "test/crypto"
   ],
   "scripts": {
     "pretest": "grunt",
@@ -33,7 +40,8 @@
     "grunt-jsbeautifier": "*",
     "grunt-contrib-jshint": "*",
     "grunt-jsdoc": "*",
-    "grunt-mocha-test": "~0.8.1"
+    "grunt-mocha-test": "~0.8.1",
+    "grunt-contrib-clean": "~0.5.0"
   },
   "dependencies": {
     "node-localstorage": "~0.3.4"