JBIDE-17625: Don't count as installable/updatable up-to-date items
JBIDE-17527 : add blurb about early access update sites

Signed-off-by: Fred Bricon <fbricon@gmail.com>
Bump parent version to 4.2.0.CR1-SNAPSHOT

Signed-off-by: Fred Bricon <fbricon@gmail.com>