Fix https for maven-default-http-blocker and update skin to 3.2.1

Maven blocks external HTTP repositories by default since version 3.8.1 (see https://maven.apache.org/docs/3.8.1/release-notes.html)

To fix this we need to update all our references in all the plugins to use https instead.
This means updating any http reference to the maven repository to https

First step would be to analyse which plugins still use http and create sub tickets for them if possible.

 The 2nd task is to update the skin to version 3.2.1

Make sure to regenerate all the docs to fix the ribbon on all doc pages.