Update server-news-4.2.0.Beta3.adoc

Fixed typo: JRE's > JREs
Update aerogear-news-1.1.0.Beta3.adoc

I've tried to "interpret" the N&N but if I have something wrong them please reject (and let me know so I can modify JBDS RNs).
Update browsersim-news-4.2.0.Beta3.adoc

Typos: plugin > plug-in
Update openshift-news-2.6.0.Beta3.adoc

Fixed typo and small edits
JBIDE-17536 use new symlink for updates/nightly/luna/ (multiple latest nightlies) instead of nightly/core/master/ (single build); also add TODO markers for what to do when we move to Mars (4.3.0)
add Beta3 to website and add TODO markers for new Beta3 blog (cc: @maxandersen)
prepare beta3 and its blog