Added autocomplete support for resources in the Opscode Database cookbook.

Added autocompletes to support the resources defined in the Opscode Database cookbook at https://github.com/opscode-cookbooks/database. All snippets are based on examples from the README.

Note: I went back and forth about whether to use the database_mysql or mysql_database shortcuts. Finally went with database_mysql, but if you think it should be reversed I'm open to the idea.

Thanks for the great project, it's saved many hours.