Update NPM dev dependencies

Author: kottenator

package.json

@@ -1,11 +1,11 @@
 {
   "private": true,
   "devDependencies": {
-    "node-sass": "*",
-    "postcss-cli": "*",
-    "autoprefixer": "*",
-    "browserify": "*",
-    "babelify": "*",
-    "babel-preset-es2015": "*"
+    "node-sass": "~3.10",
+    "postcss-cli": "~2.6",
+    "autoprefixer": "~6.5",
+    "browserify": "~13.1",
+    "babelify": "~7.3",
+    "babel-preset-es2015": "~6.16"
   }
 }