rewrite S3 poller, adds v2 metadata support
rewrite S3 poller, adds v2 metadata support

* Expect package metadata to be world readable and bucket to be
  world-listable.
* cache package manifests, only download new ones (but delete ones that
  have been removed).
TODO:
* platform name map file support is busted until release.rb is updated
  to publish it to the new metadata bucket
* suppress debug output when running under cron (append to a log?)

chef/opscode-omnitruck,chef/opscode-omnitruck,rhass/opscode-omnitruck,chef/omnitruck,chef/omnitruck,juliandunn/opscode-omnitruck,juliandunn/opscode-omnitruck,glennmatthews/opscode-omnitruck,glennmatthews/opscode-omnitruck,juliandunn/opscode-omnitruck,chef/opscode-omnitruck,chef/omnitruck,rhass/opscode-omnitruck,rhass/opscode-omnitruck,glennmatthews/opscode-omnitruck