Remove .nodemonignore file.

Adding configuration files for every tool used will clutter up the
repository, especially for a configuration as simple as this.

.nodemonignore

@@ -1,2 +0,0 @@
-build/
-dist/

package.json

@@ -107,6 +107,6 @@
     "test": "standard && depcheck --ignores=buble,nodemon,gh-release --ignore-dirs=build,dist && node ./bin/extra-lint.js",
     "gh-release": "gh-release",
     "update-authors": "./bin/update-authors.sh",
-    "watch": "nodemon --exec \"npm run start\" --ext js,pug,css"
+    "watch": "nodemon --exec \"npm run start\" --ext js,pug,css --ignore build/ --ignore dist/"
   }
 }