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.

edmunds-chef/application,hussainaphroj/application,SocialCentivPublic/application,cookbooks/oc-application,poise/application,javrasya/application,h4ck3rm1k3/application,chenliu0831/application