LTSV scanner

I've written a Coderay scanner for [LTSV (Labeled Tab-Separated Values)](http://ltsv.org/) which is a text format like below:

```plain
host:127.0.0.1<TAB>ident:-<TAB>user:frank<TAB>time:[10/Oct/2000:13:55:36 -0700]<TAB>req:GET /apache_pb.gif HTTP/1.0<TAB>status:200<TAB>size:2326<TAB>referer:http://www.example.com/start.html<TAB>ua:Mozilla/4.08 [en] (Win98; I ;Nav)
```

It is mainly used for logs and actually supported by [fluentd](http://fluentd.org/), a log collector.

I use this format for logging web servers and applications, and watching it with [ltsview](https://github.com/naoto/ltsview), but it is difficult to recognize labels or values. So I wrote the scanner to color them.

Thanks.