Code coverage and integrate codecov.io (#522)

* Add codecov and script for coverage

* Change test to test-ci in travis and appveyor config

* Add coverage badge

.travis.yml

@@ -5,6 +5,6 @@ node_js:
   - '8'
 cache: yarn
 script: 
-  - yarn test
+  - yarn test-ci
   - yarn lint
 sudo: false

README.md

@@ -7,6 +7,7 @@
 [![Backers on Open Collective](https://opencollective.com/parcel/backers/badge.svg)](#backers) [![Sponsors on Open Collective](https://opencollective.com/parcel/sponsors/badge.svg)](#sponsors)
 [![Travis CI Build Status](https://travis-ci.org/parcel-bundler/parcel.svg?branch=master)](https://travis-ci.org/parcel-bundler/parcel)
 [![Appveyor Build status](https://ci.appveyor.com/api/projects/status/nr7d6qjxj3wwsw6n?svg=true)](https://ci.appveyor.com/project/devongovett/parcel)
+[![Coverage](https://img.shields.io/codecov/c/github/parcel-bundler/parcel/master.svg)](https://codecov.io/github/parcel-bundler/parcel/)
 [![David Dependancy Status](https://david-dm.org/parcel-bundler/parcel.svg)](https://david-dm.org/parcel-bundler/parcel)
 [![npm package](https://img.shields.io/npm/v/parcel-bundler.svg)](https://www.npmjs.com/package/parcel-bundler)
 [![npm package](https://img.shields.io/npm/dm/parcel-bundler.svg)](https://www.npmjs.com/package/parcel-bundler)

appveyor.yml

@@ -15,7 +15,7 @@ test_script:
   - node --version
   - yarn --version
   # run tests
-  - yarn test
+  - yarn test-ci
   # run ESlint
   - yarn lint
 

package.json

@@ -65,10 +65,14 @@
     "prettier": "^1.9.1",
     "rimraf": "^2.6.1",
     "stylus": "^0.54.5",
-    "typescript": "^2.6.2"
+    "typescript": "^2.6.2",
+    "codecov": "^3.0.0"
   },
   "scripts": {
     "test": "cross-env NODE_ENV=test mocha",
+    "test-coverage": "rm -rf coverage/* && nyc yarn test",
+    "report-coverage": "nyc report --reporter=lcov && codecov",
+    "test-ci": "yarn test-coverage && yarn report-coverage",
     "format": "prettier --write './{src,bin,test}/**/*.{js,json,md}'",
     "build": "yarn minify && babel src -d lib && ncp src/builtins lib/builtins",
     "prepublish": "yarn build",