use composite site of multiple versions of JBT instead of single latest site as it's more resilient to frequent builds (JBIDE-17536) >> master

/builds/ is a composite of many builds' update sites
/updates/ is a single (latest) update site

As YMMV, we produce both because every year or two, someone complains loudly about needing one or the other solution. If we make /updates/ a composite for /master/ then it would be a different paradigm for /4.2.luna/, and that would be even more confusing and prone to people complaining it's inconsistent.

Make sense?