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.

sous-chefs/haproxy,rightscale-cookbooks-contrib/haproxy,flydata/haproxy,sous-chefs/haproxy,lmickh/haproxy,gocardless-cookbooks/haproxy,SocialCentivPublic/haproxy,bitpusher-real/haproxy,Youscribe/haproxy-cookbook,Dreeg/haproxy,lmickh/haproxy,bitpusher-real/haproxy,freerobby/haproxy,flydata/haproxy,andrewgoktepe/haproxy,Dreeg/haproxy,bitpusher-real/haproxy,Youscribe/haproxy-cookbook,gocardless-cookbooks/haproxy,cookbooks/oc-haproxy,hw-cookbooks/haproxy,lmickh/haproxy,gocardless-cookbooks/haproxy,Youscribe/haproxy-cookbook,SocialCentivPublic/haproxy,rightscale-cookbooks-contrib/haproxy,andrewgoktepe/haproxy,SocialCentivPublic/haproxy,rightscale-cookbooks-contrib/haproxy,hw-cookbooks/haproxy,andrewgoktepe/haproxy,Dreeg/haproxy,cookbooks/mc-haproxy