chore(nyc): switch from istanbul to nyc for coverage reporting

Closes #129

Author: fh1ch

.gitignore

@@ -2,3 +2,4 @@ node_modules/
 npm-debug.log
 reports/
 docs/
+.nyc_output/

.travis.yml

@@ -14,7 +14,7 @@ jobs:
         - "commitlint-travis"
         - "npm run lint"
         - "npm run test"
-        - "cat ./reports/coverage/lcov.info | ./node_modules/.bin/coveralls"
+        - "cat ./reports/coverage-test/lcov.info | ./node_modules/.bin/coveralls"
         - "npm run integration"
         - "npm run docs"
     - stage: compliance

package.json

@@ -6,9 +6,9 @@
   "scripts": {
     "changelog": "commitlint --from=master",
     "lint": "jshint lib/ test/ index.js && jscs lib/ test/ index.js",
-    "test": "istanbul cover --dir reports/coverage node_modules/mocha/bin/_mocha -- test/unit/*.spec.js",
-    "integration": "istanbul cover --dir reports/coverage node_modules/mocha/bin/_mocha -- test/integration/*.spec.js",
-    "compliance": "istanbul cover --dir reports/coverage node_modules/mocha/bin/_mocha -- test/compliance/*.spec.js",
+    "test": "nyc --reporter=lcov --reporter=text-summary --report-dir reports/coverage-test mocha test/unit/*.spec.js",
+    "integration": "nyc --reporter=lcov --reporter=text-summary --report-dir reports/coverage-integration mocha test/integration/*.spec.js",
+    "compliance": "nyc --reporter=lcov --reporter=text-summary --report-dir reports/coverage-compliance mocha test/compliance/*.spec.js",
     "docs": "jsdoc -d ./docs -t node_modules/docdash ./lib ./index.js ./README.md"
   },
   "repository": {
@@ -48,10 +48,10 @@
     "@commitlint/travis-cli": "^7.5.1",
     "chai": "^4.2.0",
     "docdash": "^1.0.2",
-    "istanbul": "^0.4.5",
     "jscs": "^3.0.7",
     "jsdoc": "^3.5.5",
     "jshint": "^2.9.5",
-    "mocha": "^5.2.0"
+    "mocha": "^5.2.0",
+    "nyc": "^13.2.0"
   }
 }