Revert "Fix SJK download url used by jmx blackbox tests"
Revert "Fix SJK download url used by jmx blackbox tests"

This reverts commit 3dee52937b4cd16b301b706a962807d0ce3bac24.

Sonatype just had temporarily hickups, I've confused sonatype
wrongly with bintray.

crate/crate,crate/crate,crate/crate