add codecoverage setup

Author: krvajal

.CONTRIBUTING.md.un~

@@ -29,4 +29,7 @@ install:
 
 script:
   - npm run lint
-  - npm test --silent
+  - npm test --silent
+
+after_success:
+  - bash <(curl -s https://codecov.io/bash)

.travis.yml

@@ -0,0 +1,9 @@
+{
+    "enabled": true,
+    "relativeSourcePath": "../src",
+    "relativeCoverageDir": "../../coverage",
+    "ignorePatterns": ["**/node_modules/**"],
+    "includePid": false,
+    "reports": ["json", "html", "lcov"],
+    "verbose": false
+}