bugfix/remove-async: removed async from script

[aleksandragrodem]

Met.no got errors because of _paq.push() got executed after the script was run. So other scripts was downloaded and run async a bit too fast. This was solved by removing the async from the script.

Roeland, feel free to correct me if the explanation is a bit off.

[Roeland-Bouvet]

Yeah, that's basically it. :)

The first matomo.js (+ hash) script is supposed to prepare some configuration for when the actual matomo.js script is loaded and executed. But because both script tags were set to be async, and the first one to finish loading would execute first, the "configuration script" would sometimes be executed too late. With only defer, and keeping the correct order in the head, we can make sure that the scripts get executed in the right order.