service & environment fields

Added:
- dictlike field DeviceEnvironment,
- ServiceCatalog proxy to CI,
- factories for a few models,
- RestrictedLookupChannel & ServiceCatalogLookup lookups.

Use it in ralph.discovery.device.
@quamilek @xor-xor @ar4s
I'm not sure what you are trying to achieve here. Docstring says "with authorization check", but you are only checking if user is authenticated (and btw, `user.is_authenticated()` returns `False` only for the `AnonymousUser`).