chore(package): update npm-dollar to version 2.2.1

Author: greenkeeper[bot]

package.json

@@ -96,7 +96,7 @@
     "basichtml": "^0.22.0",
     "coveralls": "^3.0.3",
     "istanbul": "^0.4.5",
-    "npm-dollar": "^2.1.3",
+    "npm-dollar": "^2.2.1",
     "rollup": "^1.10.0",
     "rollup-plugin-babel": "^4.3.2",
     "rollup-plugin-node-resolve": "^4.2.2",