1.5 plugin repos now EOL

I don't think I've announced this on previous releases, but for
everybody's information, the 1.5 plugin repos will no longer receive any

Typically we keep three major versions, plus nightlies refreshed and
tested at any one time, so that is now: 1.6, 1.7, 1.8 and nightlies.

When a plugin is updated, we can apply (retag or rebuild) the update to
any of those versions, often nightlies + 1, depending on what the
plugin's compatible with and what plugin authors request.

··· -- Dominic Cleal Red Hat Engineering