(feature request) timeout for pandas.io.json.read_json
Please allow to set a `timeout` in (all) your internet requests. We have just identified a halting problem in a repeating long runner when using `read_json()`.

Example:

```
pandas.io.json.read_json(url, timeout=10.0)
```

My current workaround is to temporarily set `socket.setdefaulttimeout(10.0)` globally (default is `None`!). Which works, but if your read_json had already allowed to set it locally, I would have probably realized much earlier.

Thanks a lot for considering this. Thanks for pandas, an amazing tool. 
