Added PostRun and PostRunError delegates
Adding modified Date helperfunction

Useful helper referenced from Brians post on forum: http://www.getsymphony.com/discuss/thread/102452/#position-10
Merge branch 'integration' of git://github.com/symphonists/xmlimporter into integration
Merge pull request #25 from andrewminton/integration

XMLImporterImportPostRun and XMLImporterImportPostRunErrors delegates added