Remove metadata.json and update application readme.
Remove metadata.json and update application readme.

* Metadata.json can be generated with the rake tasks.
* Use 'metadata[cookbook]' and 'metadata_all' to generate .json.
* Application readme needed a few more clarification points.

engineyard/ubuntu,cookbooks/oc-ubuntu,chef-cookbooks/ubuntu,robertosilvino/ubuntu,robertosilvino/ubuntu,guilhem-cookbooks/ubuntu,n0ts/ubuntu,ushios/ubuntu,engineyard/ubuntu,gensen/ubuntu,brodock/chef-ubuntu,chef-cookbooks/ubuntu,opscode-cookbooks/ubuntu,opscode-cookbooks/ubuntu,jtimberman/ubuntu,kendrickm/ubuntu