Provide Internet Explorer support

Tip submitted by @wmarques

JHipster supports only evergreen browsers. However you can still easily support some older browsers like Internet Explorer.

In order to do that you have to:

1. Set target to es5 in your tsconfig
2. Then you have two options:
   1. Add the correct polyfills from ‘core-js’, if you don’t know which one you should use, check the Angular CLI project and their polyfills.
   2. Or use babel + Babel preset-env to automatically import the correct core-js polyfills based on a browserslist file.