Add a test targeting BZ 1151220

Clients must submit a nested hash of attributes to certain API URLs.

For example, POSTing this data to the `/architectures` URL will succeed:

    {'name': 'foo'}

However, these operating system IDs will be silently ignored:

    {'name': 'foo', 'operatingsystem_ids': [1, 2, 3]}

A client can hack around this oddity by wrapping submitted data inside an extra
hash:

    {'architecture': {'name': 'foo', 'operatingsystem_ids': [1, 2, 3]}}

This extra hash should not be necessary. It makes the API harder to use, and
the extra hash is only required for some API calls.