Enable style configuration

I supported custom style feature of percol.

## Original
Originally, you can write custom style like:
```python
percol.view.CANDIDATES_LINE_BASIC    = ("on_default", "default")
percol.view.CANDIDATES_LINE_SELECTED = ("underline", "on_yellow", "white")
percol.view.CANDIDATES_LINE_MARKED   = ("bold", "on_cyan", "black")
percol.view.CANDIDATES_LINE_QUERY    = ("yellow", "bold")
```

## Peco version
In this pull req, I supported them except "marked".
After merging this pull req, you'll be able to configure like:
```json
{
    "Style": {
        "Basic": ["on_default", "default"],
        "Selected": ["underline", "on_cyan", "black"],
        "Query": ["yellow", "bold"]
    }
}
```

## Demo
By this config.json, you'll see:
![](https://gist.githubusercontent.com/k0kubun/d211d8ee67df64610e0c/raw/zsh.png)