Allow passing host to database resource

According to [COOK-3925](https://tickets.opscode.com/browse/COOK-3925) I've added `host` option to allow `knife solo` to specify database options.

Usage example:

``` ruby
application "my-app" do
  rails do
    database do
      host '127.0.0.1'
      database 'name'
      quorum 2
      replicas %w[Huey Dewey Louie]
    end
  end
end
```