Add announcement of Gothenburg user summit registration open

The permalink is backdated to 15th March which is when Luca
announced registration open on the mailing list.

Change-Id: I92fe3239cc3196c4b12c72ea01678b710fbd4719
diff --git a/_posts/2019-03-16-user-summit-gothenburg-registration-open.md b/_posts/2019-03-16-user-summit-gothenburg-registration-open.md
new file mode 100644
index 0000000..660db89
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+++ b/_posts/2019-03-16-user-summit-gothenburg-registration-open.md
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+---
+title: Gerrit User Summit 2019 Registration is Open
+tags: news, summit, hackathon
+keywords: news, summit, hackathon
+permalink: 2019-02-27-user-summit-gothenburg-registration-open.html
+summary: "Registration for the Gerrit User Summit 2019 is now open"
+hide_sidebar: true
+hide_navtoggle: true
+toc: true
+---
+
+Registration for Gerrit User Summit 2019 is now open on
+[gus2019.eventbrite.com](https://gus2019.eventbrite.com).
+
+You can request also the participation to the Hackathon in the form. If you are a
+maintainer, your request is automatically accepted. For all the other requests, we
+will allocate slots for contributors and even for all of those who never contributed
+to Gerrit but are willing to learn and start extending and using Gerrit API.