remote_syslog advanced config

I've done the following:

* Version bump in `metadata.rb`
* `CHANGELOG.md` entry
* Added additional config as attributes as per https://github.com/papertrail/remote_syslog/blob/master/examples/log_files.yml.example.advanced
* Refactored the `log_files.yml` template variables to be a `.to_yaml` and updated the template to match.

Works for me, I put in:

```json
"default_attributes": {
  "remote_syslog": {
    "init_style": "init",
    "destination": {
      "host": "logs.papertrailapp.com",
      "port": "12345"
    },
    "conf": {
      "files": [
        "/var/log/*.*",
        "/var/log/nginx/*.log",
        "/var/log/php-fpm.log"
      ] 
    }
  }
}
```
and get out: 
```yaml
$ cat /etc/log_files.yml 

files:
- /var/log/*.*
- /var/log/nginx/*.log
- /var/log/php-fpm.log
exclude_files:
hostname: the-servers-name
parse_fields: 
prepend: 
exclude_patterns:
destination:
  host: logs.papertrailapp.com
  port: '12345'
```