Releng : Landing page for p2 repositories

1. The generator should only attempt to write a file if the file doesn't
   already exist with the required content. This helps in the update
   scenario with some version control systems as it avoids unnecessary
   file changes.
   
2. The generator should have a way of excluding files and folders from
   the listing pages.
Releng : Landing page for p2 repositories

ResourceCollection is not Iterable in the Ant 1.8.2 release.