Simplify cover and coveralls scripts for local and travis

.travis.yml

@@ -1,7 +1,5 @@
 language: node_js
 node_js:
 - "stable"
-before_script:
-- npm install -g istanbul
 after_success:
-- istanbul cover ./node_modules/mocha/bin/_mocha --report lcovonly -- -R spec && cat ./coverage/lcov.info | ./node_modules/coveralls/bin/coveralls.js && rm -rf ./coverage
+- npm run coveralls

package.json

@@ -4,8 +4,9 @@
   "description": "Generate Pythagorean triples using Euclid's formula",
   "main": "index.js",
   "scripts": {
-    "test": "./node_modules/mocha/bin/mocha",
-    "coverage": "./node_modules/istanbul/lib/cli.js cover ./node_modules/mocha/bin/_mocha"
+    "test": "mocha",
+    "cover": "istanbul cover _mocha",
+    "coveralls": "npm run cover -- --report lcovonly && cat ./coverage/lcov.info | coveralls && rm -rf ./coverage"
   },
   "repository": {
     "type": "git",