[JBIDE-16724] add clean plugin into pluginManagement
[JBIDE-16747] Add jbosstools-sim nightly p2repository definition to parent/pom.xml
reorder jbosstools-*-site entries so that new jbosstools-sim-site is listed after base and aerogear, on which it depends, not after gwt/freemarker/birt, which are static/unchanging sites
JBIDE-16747 Max/Denis request we remove the ref to new sim site pending its creation (and naming)
set parent pom version 4.2.0.Beta2-SNAPSHOT in master
set tycho version = 0.20.0 in master branch (JBT 4.2.0.Beta2)
BIRT is now building in master and Beta1x branch, so replace jbosstools-birt-site=http://download.jboss.org/jbosstools/updates/stable/kepler/core/birt/ with jbosstools-birt-site = staging/jbosstools-birt_* site
Use new TP 4.40.0.Beta2-SNAPSHOT
JBIDE-16960 remove jbosstools-gwt-site = http://download.jboss.org/jbosstools/updates/stable/juno/core/gwt/ as no longer needed