No redirect to formspree after message sent

[NiklasLehnfeld]

First of all: Great work with this template! It's awesome. I also use it for my personal website! And have a change-request:

There is no real need of redirecting to formspree after a successful message was sent.
When following the formspree react example its also working without a redirect. Would be a way better user experience.

I prepared a pullrequest (#29) for that. For backwards compatibility I didn't changed the metadata field formspreeEndpoint. Even when a formspreeId would be better.

Let me know what you think.

[NiklasLehnfeld]

Hey @wkocjan. Is here still someone active on this repository?
I would really like to add more improvements in the future to that side, since I would really like to stick to this template. But if I don't get a way to get my changes into your repository I would need to publish it on my own somewhere.