remove chai stats because of chaijs/chai-stats#5

Author: mcous

packages/gerber-plotter/package.json

@@ -42,7 +42,6 @@
   "devDependencies": {
     "babelify": "^6.3.0",
     "chai": "^3.2.0",
-    "chai-stats": "^0.3.0",
     "coveralls": "^2.11.4",
     "eslint": "^1.3.1",
     "istanbul": "^0.4.0",