Fix default style

After merging https://github.com/lestrrat/peco/pull/59, I noticed that I broke original behavior.
Because I've set all style `termbox.ColorDefault`, selected line and query word are not highlighted.
This is not intended, so I fixed that. Sorry.

## before (unintended)
![](https://gist.github.com/k0kubun/d211d8ee67df64610e0c/raw/8bb69bf2f76f0a8502e08df3545a60e806eed568/before.png)

## after 
![](https://gist.github.com/k0kubun/d211d8ee67df64610e0c/raw/a1cde586872edcaaf3617e79bacc728b77ad0668/after.png)