[HEAD-302] fix algorithm for detecting newest tarball to work with 'git describe' format
[HEAD-302] fix algorithm for detecting newest tarball to work with 'git describe' format

kaizengarden/sdc-headnode,numericillustration/sdc-headnode,joyent/sdc-headnode,joyent/sdc-headnode,joyent/sdc-headnode,kaizengarden/sdc-headnode,kaizengarden/sdc-headnode,joyent/sdc-headnode,numericillustration/sdc-headnode,numericillustration/sdc-headnode,kaizengarden/sdc-headnode