feat(scripts): add size script to get gzipped build size for umd bundle

package.json

@@ -2,9 +2,9 @@
   "name": "typescript-lib-starter",
   "version": "1.2.0",
   "description": "TypeScript library setup for multiple compilation targets using tsc and webpack",
-  "main": "lib/index",
-  "module": "lib-esm/index",
-  "jsnext:main": "lib-esm/index",
+  "main": "lib/index.js",
+  "module": "lib-esm/index.js",
+  "jsnext:main": "lib-esm/index.js",
   "umd:main": "umd/typescript-lib-starter.min.js",
   "typings": "typings/index.d.ts",
   "repository": "https://www.github.com/Hotell/typescript-lib-starter",
@@ -33,7 +33,8 @@
     "release:github": "git push --no-verify --follow-tags origin master",
     "release:npm": "npm publish",
     "release:preflight": "irish-pub",
-    "release:preflight:package": "npm pack"
+    "release:preflight:package": "npm pack",
+    "size": "shx echo \"Gzipped Size:\" && cross-var strip-json-comments --no-whitespace $npm_package_umd_main | gzip-size"
   },
   "config": {
     "commitizen": {
@@ -48,11 +49,14 @@
   "devDependencies": {
     "awesome-typescript-loader": "3.0.8",
     "commitizen": "2.9.6",
+    "cross-var": "1.0.2",
     "cz-conventional-changelog": "2.0.0",
+    "gzip-size-cli": "2.0.0",
     "husky": "0.13.1",
     "irish-pub": "0.2.0",
     "shx": "0.2.2",
     "standard-version": "4.0.0",
+    "strip-json-comments-cli": "1.0.1",
     "tslint": "4.5.0",
     "tslint-react": "2.4.0",
     "typescript": "2.2.1",