chore: add coverage

Add coverage to the project

.gitignore

@@ -1,4 +1,4 @@
 node_modules
 coverage
 .idea
-
+.nyc_output/

.travis.yml

@@ -16,3 +16,5 @@ addons:
       - mongodb-org-shell
 services:
   - mongodb
+
+after_success: npm run coverage

package.json

@@ -8,10 +8,11 @@
   "author": "IBM Corp.",
   "main": "index.js",
   "scripts": {
+    "coverage": "nyc report --reporter=text-lcov | coveralls",
     "benchmarks": "make benchmarks",
     "leak-detection": "make leak-detection",
     "coverage": "nyc report --reporter=text-lcov | coveralls",
-    "test": "mocha test/*.test.js node_modules/juggler-v3/test.js node_modules/juggler-v4/test.js",
+    "test": "nyc mocha test/*.test.js node_modules/juggler-v3/test.js node_modules/juggler-v4/test.js",
     "lint": "eslint .",
     "posttest": "npm run lint"
   },
@@ -38,12 +39,14 @@
   "devDependencies": {
     "benchmark": "^2.1.4",
     "bluebird": "^3.5.4",
+    "coveralls": "^3.0.4",
     "eslint": "^5.1.0",
     "eslint-config-loopback": "^13.0.0",
     "juggler-v3": "file:./deps/juggler-v3",
     "juggler-v4": "file:./deps/juggler-v4",
     "loopback-datasource-juggler": "^3.0.0 || ^4.0.0",
     "mocha": "^5.2.0",
+    "nyc": "^14.1.1",
     "rc": "^1.2.8",
     "semver": "^5.5.1",
     "should": "^13.2.1",