Cannot supply additional monitors

From `attributes/cloud_monitoring.rb`:
```
# Currently for service monitoring, the recipe that sets up the service should add:
# node.default['platformstack']['cloud_monitoring']['service']['name'].push('<service_name>')
default['platformstack']['cloud_monitoring']['service']['name'] = []
default['platformstack']['cloud_monitoring']['service']['disabled'] = false
default['platformstack']['cloud_monitoring']['service']['alarm'] = false
default['platformstack']['cloud_monitoring']['service']['period'] = 60
default['platformstack']['cloud_monitoring']['service']['timeout'] = 30
default['platformstack']['cloud_monitoring']['service']['cookbook'] = 'platformstack'
default['platformstack']['cloud_monitoring']['service_mon']['cookbook'] = 'platformstack'
```

This only configures monitors using an existing `service_mon.sh` template. There is no way to configure a custom template.