Continuation of Songkick pull request (309)

This is a continuation of [pull request #309](https://github.com/duckduckgo/zeroclickinfo-spice/pull/309). It addresses the list of topics, putting `jsoncallback` in the API url, using the default `proxy_cache_valid`, and changing to the list template frame.

Similar artists, closed:
![artists_like_eric_clapton_closed](https://f.cloud.github.com/assets/48050/1505015/21a6aa22-48ca-11e3-9f92-e75032d650fb.png)

Similar artists, open:
![artists_like_eric_clapton_open](https://f.cloud.github.com/assets/48050/1505017/25c2005c-48ca-11e3-84c4-7c228fba2da9.png)

Concerts, closed:
![concerts_in_nyc_closed](https://f.cloud.github.com/assets/48050/1505018/2c847672-48ca-11e3-8a56-188033bcfe9b.png)

Concerts, open:
![concerts_in_nyc_open](https://f.cloud.github.com/assets/48050/1505019/2fba20f8-48ca-11e3-93a7-8d35f2626a8a.png)

Incidentally, I discovered that it is not necessary to specify `spice_name` in the `Spice.render()` call if not using a template frame, but it is necessary if using the list template frame (and possibly others).