add eslint script

Author: jeremydaly

package.json

@@ -6,7 +6,8 @@
   "scripts": {
     "test": "mocha --check-leaks --recursive",
     "test-cov": "nyc --reporter=lcov mocha --check-leaks --recursive",
-    "test-ci": "nyc npm test && nyc report --reporter=text-lcov | ./node_modules/coveralls/bin/coveralls.js"
+    "test-ci": "nyc npm test && nyc report --reporter=text-lcov | ./node_modules/coveralls/bin/coveralls.js",
+    "lint": "eslint ."
   },
   "repository": {
     "type": "git",