Add support for node authentication on smart-proxy
Use sha256 for authentication instead of sha1

  * Add also a parameter in client.rb
Set '/etc/chef/client.pem' as default private key path
Merge pull request #4 from rvrignaud/chefproxy

First support of node authentication on smart-proxy
Add new report uploader based on ResourceReporter

Also refactored uploading class
Gemified version