Upgrade to Bootstrap 4 and review JS code

[Nordes]

Due to the upgrade from Bootstrap 3 to 4, a lot of things had to change. So, I've rebuilt the menu and added the fontawesome icons in order to keep the UI consistent with what you had.

I've also

• applied some style to the table (where we display the generated data).
• added style on buttons in the counter page
• removed unnecessary global component in order to keep only the icons as global.
• fix the active link using the router property
• updated all the packages
• added in the webpack the popper.js (Not included anymore within bootstrap 4).
• added the license and repository in the package,json
• added a spinner in the fetching data (just in case someone want a sample, but I didn't put any time sleep in order to fake data lag).

C# part haven't been modified.

[MarkPieszak]

This looks great! Nice work 🥇

[Nordes]

Here's a screenshot. It would also be nice to have on the main readme.md.