Piwik insertion code is outdated, slows page loading

The current code for piwik (in WEB-INF/template/scripts.xhtml) is outdated, and causes browser warnings like this one (thus breaking our tests):

WARNING: 06:23:16.556 http://localhost:48830/zanata/?dswid=-9554 109:16 A Parser-blocking, cross-origin script, http://example.com/piwik/piwik.js, is invoked via document.write. This may be blocked by the browser if the device has poor network connectivity.

This seems to be the current tracking code: