TemplateConfig implementation with Kubernetes

Initial implementation of TemplateConfig REST endpoint.

See the project.json example.

To test this PR:

```
$ curl -d @pkg/template/examples/project.json \
  http://localhost:8080/api/v1beta1/templateConfigs
```

This will return `Config{}` which is essentially the same as a `templateConfig{}` but without parameters.

**FYI**: This is a wip, all commits will be squashed in the end. @VojtechVitek is working on validation atm. so I don't want to force push ;-)
Yeah - cause at least a Go client will have a TemplateConfig object, so for them they can just say "read template config from disk, override parameter X".

This is a good pattern in general in Kubernetes - making the API objects composable so that your client code on both the server or in a CLI can do the same thing the same way.