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 ;-)
You mean that when we generate `Config` from `templateConfig`, we will need to iterate over the []interface{} and have type switch and then cast the objects we do know (or are registered).

Then for serialization, we just override the Items content to be []knownAPIObject ?