Consider lazy loading of Camel models

[tadayosi]

Since we support multiple versions of Camel model #693, we need to bundle all the model defintions in the hawtio/react distribution. We lately found that it's bloating the distribution files and thus decreasing the performance of initial loading of the console.

One possible solution to deal with the performance issue would be to introduce lazy loading for the Camel models, so that they are not fetched from the server until it's really necessary and even that unused models are never loaded.