Add build to release script.

package.json

@@ -12,6 +12,7 @@
     "build": "rollup -c && rollup -c rollup.config.min.js",
     "build-docs": "jsdoc2md -f src/dat/gui/GUI.js src/dat/controllers/Controller.js src/dat/controllers/NumberController.js | replace-between --target API.md --token API",
     "lint": "eslint src",
+    "version": "npm run build && git add -A build",
     "postversion": "git push && git push --tags && npm publish"
   },
   "repository": {

rollup.config.js

@@ -37,7 +37,10 @@ export default {
   },
   plugins: [
     resolve(),
-    sass({options: {outputStyle: 'compressed'}}),
+    sass({
+      output: 'build/dat.gui.css',
+      options: {outputStyle: 'compressed'}
+    }),
     babel({
       plugins: ['external-helpers'],
       exclude: 'node_modules/**'