Remove duplication from generated bundles.yaml

After you generate deployment with `python charmgen/generator.py 180` command you'll see that it has duplications in relations section, for instance: 
```yaml
  - - dea:ltc
    - - loggregator-trafficcontrol:ltc
    - - loggregator-trafficcontrol:ltc
    - - loggregator-trafficcontrol:ltc
```
This PR fixes it.