P2 update implementation and editor version extraction

P2 update implementation and editor version extraction

ApplicationWorkbenchAdvisor : clean up
ApplicationWorkbenchWindowAdvisor : added update of editor to startup
P2Util : replaced older class with a new one which handles background update of editor
UpdateHandler : handles modal update of editor when requested
InstallNewSoftwareHandler, PreloadingRepositoryHandler : handlers for installing new software and preloading repositories (not used yet)
ApplicationUtil : added new methods to retrieve editor version number
TaxonomicEditorPlugin : added new methods for retrieving provisioning elements
build.properties, pom.xml, plugin_en.properties, plugin.properties, plugin_de.properties : setup dynamic properties (version number , build date) to be replaced via maven
plugin.xml, MANIFEST.MF : added new dependencies for p2 update mechanism
p2.inf : deleted since we now setup update repositories programmatically