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.

cookbooks/nd-chef-opscode-rabbitmq,brumschlag/rabbitmq,DonorsChoose/chef-rabbitmq,jujugrrr/rabbitmq,cookbooks/mc-rabbitmq,gocardless-cookbooks/rabbitmq,GannettDigital/chef-rabbitmq,jdrago999/rabbitmq,scalp42/rabbitmq,ssevertson/rabbitmq,jjasghar/rabbitmq,ssevertson/rabbitmq,kri5/rabbitmq,sendgrid-ops/rabbitmq,jingzhaoou/rabbitmq,XiangYao/rabbitmq,behanceops/rabbitmq,jjasghar/rabbitmq,philipbalinov/rabbitmq,ssevertson/rabbitmq,jujugrrr/rabbitmq,kri5/rabbitmq,justanshulsharma/rabbitmq,scalp42/rabbitmq,yangchengjian/rabbitmq,justanshulsharma/rabbitmq,jdrago999/rabbitmq,jordant/rabbitmq,cookbooks/oc-rabbitmq,PerfectMemory/rabbitmq,XiangYao/rabbitmq,behanceops/rabbitmq,rogerhu/rabbitmq,nipe0324/rabbitmq,yangchengjian/rabbitmq,rogerhu/rabbitmq,farshidce/rabbitmq,zenoss/rabbitmq,jordant/rabbitmq,philipbalinov/rabbitmq,keepgo/rabbitmq,gocardless-cookbooks/rabbitmq,brumschlag/rabbitmq,sethcall/rabbitmq,FishkinsDC/chef-rabbitmq,farshidce/rabbitmq,phusion/chef-rabbitmq-cookbook,Pando6/rabbitmq-cookbooks,jingzhaoou/rabbitmq,PerfectMemory/rabbitmq,keepgo/rabbitmq,GannettDigital/chef-rabbitmq,nipe0324/rabbitmq,sendgrid-ops/rabbitmq