The data posted to the `set_permissions` endpoint is currently sent as a
list of permissions:
`[{'permission': MANAGE_SETTINGS}, {'permission': MANAGE_TEMPLATES}]`.
This endpoint is going to also be used for folder permissions, so the
data now needs to be nested:
`{'permissions': [{'permission': MANAGE_SETTINGS}, {'permission': MANAGE_TEMPLATES}]}`
This changes the set_permissions endpoint to accept data in either
format. Once admin is sending data in the new format, the code can be
simplified.