Fix filter order when concatenating all the fragments

The current command (cat /var/vcap/packages/logstash-filters-*/*.conf ) results in the following order:
```
/var/vcap/packages/logstash-filters-cf/100-cloudfoundry.conf
/var/vcap/packages/logstash-filters-common/75-elasticsearch_request.conf
/var/vcap/packages/logstash-filters-common/75-nginx_combined.conf
```

From my understanding, the desired state is to have it like so:
```
/var/vcap/packages/logstash-filters-common/75-elasticsearch_request.conf
/var/vcap/packages/logstash-filters-common/75-nginx_combined.conf
/var/vcap/packages/logstash-filters-cf/100-cloudfoundry.conf
```

This would be more pronounced if more filters existed with varying numering scheme between the different folders, for example:
```
/var/vcap/packages/logstash-filters-cf/30-third_filter.conf
/var/vcap/packages/logstash-filters-cf/100-cloudfoundry.conf
/var/vcap/packages/logstash-filters-common/20-second_filter.conf
/var/vcap/packages/logstash-filters-common/75-elasticsearch_request.conf
/var/vcap/packages/logstash-filters-common/75-nginx_combined.conf
/var/vcap/packages/logstash-filters-xyz/10-first_filter.conf
```

The find fixes this by sorting based on filename alone, irrespective of the folder it sits in (even if they were subfolders).