Update example to Parse Server 8

[dblythy]

The example project uses a number of outdated approaches, and should be updated accordingly.

Approach:

• use module syntax and .start
• simplify testing

[parse-github-assistant]

Thanks for opening this issue!

[mtrezza]

I'd say let's update to PS8 once there's stable release, in a few days.

[mtrezza]

Could you use the latest alpha release of PS8? Before we merge we'll upgrade to a stable release.

[parseplatformorg]

🎉 This change has been released in version 3.0.0