Update babel7 to the latest version 🚀 (#1273)

* chore(package): update @babel/core to version 7.6.0

* chore(package): update @babel/plugin-proposal-decorators to version 7.6.0

* chore(package): update @babel/plugin-transform-runtime to version 7.6.0

* chore(package): update @babel/preset-env to version 7.6.0

* fix(package): update @babel/runtime to version 7.6.0

* chore(package): update lockfile package-lock.json

Author: greenkeeper[bot]