Add PUT and PATCH on models/{modelname}/acls endpoint.

I've tried to keep the --auth and hawk things on a new line to be easier to read:

```
http GET http://localhost:8000/models/todo/acls --verbose \
--auth-type=hawk  --auth='504fd8148d7cdca10baa3c5208b63dc9e13cad1387222550950810a7bdd72d2c:'
```