BUG/API: autocorrelation_plot should accept kwargs
Unless there's a specific reason not to for this plot?  All the others seem to accept them.

``` python
autocorrelation_plot(data, label='ACF')
```

![label_autocorr](https://f.cloud.github.com/assets/1312546/1649385/4cad26d2-59fb-11e3-9d3e-2ccc7c44856e.png)

can you rebase, and move release notes to 0.13.1..thxs
 @TomAugspurger can you rebase and move notes to 0.13.1..thxs
 @jreback rebased and moved to 0.13.1. Sorry I missed the earlier ping, I think my email settings were messed up.

This whole plotting function needs a bunch of work, but I guess this is a patch. I'll try to get back to this later.
 thanks @TomAugspurger pls look thru plotting issues at your leisure and do some PR's!
