`create-policy` should warn that it cannot create tags

When the user runs an outdated `create-policy` command that was intended to
create a tag, the user sees the unhelpful: `error: tags[0] should be a string,
but was actually a object`. This should instead read: `error: this command can
no longer create tags; see `razor help create-tag``.

Fixes https://tickets.puppetlabs.com/browse/RAZOR-336