package.json: exit mocha after tests are done; mochajs/mocha#3044

Signed-off-by: Mario Kozjak <kozjakm1@gmail.com>

package.json

@@ -6,7 +6,7 @@
   "scripts": {
     "build": "mkdir -p ./dist && eslint --fix -c ./.eslintrc './src/**/*.js' './test/**/*.js' && babel ./src -d ./dist && browserify -s RPCWebSocket ./dist/index.browser.js > ./dist/index.browser-bundle.js",
     "pretest": "npm run-script build",
-    "test": "mocha test/*spec.js",
+    "test": "mocha --exit test/*spec.js",
     "coverage": "istanbul cover _mocha --report lcovonly -- -R spec",
     "coveralls": "npm run-script coverage && coveralls < ./coverage/lcov.info"
   },