include Juno SR1+ performance fix as new connector on Central

Info: https://bugs.eclipse.org/bugs/show_bug.cgi?id=385272, http://wiki.eclipse.org/Platform_UI/Juno_Performance_Investigation
Update Site: http://download.eclipse.org/eclipse/updates/4.2 --> Eclipse UI Juno SR1 Optimizations should be installed

For Juno SR2 maintenance builds >= Nov 21, patch feature not needed.

We could also consider setting these vmargs when installing JBT (community cental feature?) and/or JBDS BYOE:

-Xmn128m
-Xms1024m
-Xmx1024m
-Xss2m
-XX:PermSize=256m
-XX:MaxPermSize=384m