Drive download links from the Web UI should be dynamic

In https://webui-demo.nuxeo.com/nuxeo/ui/#!/drive the download links are hardcoded:
http://community.nuxeo.com/static/drive//latest/8.3/nuxeo-drive.dmg
http://community.nuxeo.com/static/drive//latest/8.3/nuxeo-drive.msi

See https://github.com/nuxeo/nuxeo-drive-server/blob/master/nuxeo-drive-web-ui/src/main/resources/web/nuxeo.war/ui/nuxeo-drive/nuxeo-drive-desktop-packages.html#L110

If we cannot access the org.nuxeo.drive.update.site.url and org.nuxeo.distribution.version Framework properties an easy workaround is to point to http://community.nuxeo.com/static/drive/latest/nuxeo-drive.dmg and http://community.nuxeo.com/static/drive/latest/nuxeo-drive.msi