Remove backup file for pom.xml
[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