moving vault access layer to pxnCommon from Listeners package

git-svn-id: http://pxncommon.googlecode.com/svn/trunk@21 f5fbd6b6-c213-558c-f92f-5ab434f62466
making pxnCommon into a library plugin
  added resource files
  onEnable() and onDisable() are now handled by pxnPlugin class
  added StartPlugin() and StopPlugin() as abstract methods
added SingleInstance() static function
renamed uniqueHistoryRND() to HistoryRND()
renamed and moved pxnListenerServer class to pxnVault

git-svn-id: http://pxncommon.googlecode.com/svn/trunk@22 f5fbd6b6-c213-558c-f92f-5ab434f62466