feat(compile): Rebuild package on file change in dev-mode

Added a npm-script for watching changes and re-compile the source file

Author: Oskar Karlsson

package.json

@@ -7,6 +7,7 @@
     "check-coverage": "istanbul check-coverage --statements 80 --branches 80 --functions 80 --lines 80 ",
     "commit": "git-cz",
     "build": "babel src --out-dir dist",
+    "build:watch": "babel --watch src --out-dir dist",
     "prepublish": "npm run build",
     "report-coverage": "cat ./coverage/lcov.info | codecov",
     "semantic-release": "semantic-release pre && npm publish && semantic-release post",