Add coverall to follow our coverage

package.json

@@ -48,6 +48,7 @@
     "js-test-karma": "karma start js/tests/karma.conf.js",
     "js-test-karma-old": "cross-env USE_OLD_JQUERY=true npm run js-test-karma",
     "js-test-cloud": "ruby -r webrick -e \"s = WEBrick::HTTPServer.new(:Port => 3000, :DocumentRoot => Dir.pwd, :Logger => WEBrick::Log.new('/dev/null'), :AccessLog => []); trap('INT') { s.shutdown }; s.start\" & node build/saucelabs-unit-test.js",
+    "coveralls": "shx cat js/coverage/lcov.info | coveralls",
     "docs": "npm-run-all --parallel css-docs js-docs --sequential docs-compile docs-lint",
     "docs-compile": "bundle exec jekyll build",
     "postdocs-compile": "npm run docs-workbox-precache",
@@ -64,7 +65,7 @@
     "release-version": "node build/change-version.js",
     "release-zip": "cd dist/ && zip -r9 bootstrap-$npm_package_version-dist.zip * && shx mv bootstrap-$npm_package_version-dist.zip ..",
     "dist": "npm-run-all --parallel css js",
-    "test": "npm-run-all dist js-test docs-compile docs-lint bundlesize",
+    "test": "npm-run-all dist js-test docs-compile docs-lint bundlesize coveralls",
     "watch": "npm-run-all --parallel watch-css watch-js",
     "watch-css": "nodemon --ignore js/ --ignore dist/ -e scss -x \"npm run css\"",
     "watch-js": "nodemon --ignore scss/ --ignore js/dist/ --ignore dist/ -e js -x \"npm run js-compile\""
@@ -95,6 +96,7 @@
     "babel-plugin-transform-es2015-modules-strip": "^0.1.1",
     "bundlesize": "^0.16.0",
     "clean-css-cli": "^4.1.11",
+    "coveralls": "^3.0.0",
     "cross-env": "^5.1.4",
     "eslint": "^4.19.0",
     "eslint-plugin-compat": "^2.2.0",