Remove model name from nickname, swagger spec understands op context.

This removes the redundancy from paths in swagger-ui such as
`/api/user/user_login`. It will now be displayed simply as
`/api/user/login`.

This is consistent with how `nickname` is used in Swagger examples.
That means to match 0 or more characters, but as few as possible, to avoid clobbering names that are intended to have dots in them. For example, see the matching [with the ?](https://www.debuggex.com/r/i5BY8uvoXPZae9Gl) versus [without](https://www.debuggex.com/r/znM50XQ8KUkmu8wH).

I suppose the `^` would be helpful, but only in the case of a name like `.foo.bar.baz`, in which case there would be no match.