JBIDE-14794 - install from central

https://issues.jboss.org/browse/JBIDE-14794
install from central shows "selection has been modified" as if p2 decided
to install something different and p2 remediation not used/shown
JBIDE-15750 - AS7.1 requirement is not met when its downloaded and installed from IDE
JBIDE-2507 Migration to org.eclipse.ui.menus

Migrated JBoss Central Help menu item and toolbar item