rename "build" script to "_build"

Mitigates NPM trying to install devDependencies when included as a dependency.

npm/cli#3902

Author: se-iurio

package.json

@@ -46,7 +46,7 @@
   ],
   "scripts": {
     "watch": "parcel watch",
-    "build": "parcel build && yarn run css",
+    "_build": "parcel build && yarn run css",
     "css": "yarn sass src/:dist/ --style compressed",
     "watch-css": "yarn sass src/:dist/ --watch --style compressed",
     "test": "karma start test/karma.conf.js",