Replace Grunt tasks with Gulp

package.json

@@ -1,25 +1,32 @@
 {
-  "name": "minimal-mistakes-theme",
-  "author": "Michael Rose <michael@mademistakes.com>",
-  "homepage": "http://mmistakes.github.io/minimal-mistakes/",
+  "name": "minimal-mistakes-jekyll-theme",
+  "version": "2.0.0",
   "repository": {
     "type": "git",
     "url": "git://github.com/mmistakes/minimal-mistakes.git"
   },
+  "keywords": [
+    "jekyll",
+    "gulp"
+  ],
+  "author": "Michael Rose",
+  "license": "MIT",
   "bugs": {
     "url": "https://github.com/mmistakes/minimal-mistakes/issues"
   },
-  "engines": {
-    "node": ">= 0.10.0"
-  },
+  "homepage": "https://github.com/mmistakes/minimal-mistakes",
   "devDependencies": {
-    "grunt": "~0.4.1",
-    "grunt-contrib-clean": "~0.5.0",
-    "grunt-contrib-jshint": "~0.6.3",
-    "grunt-contrib-uglify": "~0.2.2",
-    "grunt-contrib-watch": "~0.5.2",
-    "grunt-recess": "~0.3.5",
-    "grunt-contrib-imagemin": "~0.2.0",
-    "grunt-svgmin": "~0.2.0"
+    "browser-sync": "^2.11.1",
+    "gulp": "^3.9.1",
+    "gulp-autoprefixer": "^3.1.0",
+    "gulp-imagemin": "^2.4.0",
+    "gulp-jshint": "^2.0.0",
+    "gulp-plumber": "^1.1.0",
+    "gulp-rename": "^1.2.2",
+    "gulp-sass": "^2.2.0",
+    "gulp-uglify": "^1.5.3",
+    "gulp-uglifyjs": "^0.6.2",
+    "imagemin-pngquant": "^4.2.2",
+    "jshint": "^2.9.1"
   }
 }