Http Server: Code generation, add template function to copy and set structure.

When working with the json objects, it is sometimes useful to copy
information from or to a structure that is define somewhere else.

This adds the ability to do that copying to any struct that has the same
fields.

Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>
Http Server: Auto code generation determine class order

When there are model inside of a model, it is required to determine
their creation order.
This set a valid order or call an error if a cyclic is found.

This also adds an assignment operator that is used by canonical models.

Signed-off-by: Amnon Heiman <amnon@cloudius-systems.com>
Signed-off-by: Pekka Enberg <penberg@cloudius-systems.com>