add coveralls integration

package.json

@@ -6,6 +6,7 @@
   "scripts": {
     "test": "npm run build && npm run unit",
     "unit": "nyc --require babel-core/register mocha test/src/**",
+    "coverage": "nyc report --reporter=text-lcov | coveralls",
     "build": "babel src --out-dir lib",
     "prepublish": "in-publish && npm run test || not-in-publish"
   },
@@ -21,6 +22,7 @@
     "babel-eslint": "~4.1.8",
     "babel-plugin-add-module-exports": "~0.1.2",
     "babel-preset-es2015": "~6.6.0",
+    "coveralls": "~2.11.9",
     "eslint": "~1.10.3",
     "eslint-plugin-mocha": "~1.1.0",
     "eslint-plugin-react": "~4.2.3",