XWIKI-11008: Allow stopping running XWiki instances when starting a new instance
XWIKI-11009: Improve argument passing in Jetty start/stop scripts
+ update XWikiExecutor to stop trying to create a Socket to check if XWiki is running since that could potentially cause some issues (locking the ports temporarily).
* Change the way variables are replaced in jetty start scripts to match what's done by the Maven Assembly plugin. This also avoids an issue with "$!" which was getting replaced by Velocity...