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.

TAKEALOT/varnish,KierranM/varnish,yoshiwaan/varnish,gsreynolds/varnish,gusrc/varnish,gsreynolds/varnish,elastera/varnish,cookbooks/oc-varnish,elastera/varnish,NREL-cookbooks/varnish,NREL-cookbooks/varnish,gusrc/varnish,rackspace-cookbooks/varnish,KierranM/varnish,GannettDigital/chef-varnish,GannettDigital/chef-varnish,rackspace-cookbooks/varnish,gusrc/varnish,rackspace-cookbooks/varnish,TAKEALOT/varnish,yoshiwaan/varnish,jujugrrr/varnish,bitzesty/varnish,jujugrrr/varnish