Add support for extensionless files in statistics and support regexp matching with --file-types.

```
What steps will reproduce the problem?
1. run gitinspector on any repo
2. have files in the repo without an extension
3. see missing commits

What is the expected output? What do you see instead?

I see only those commits against files with extensions.

What version of the product are you using? What version of Python? On what
operating system?

Ubuntu-14.04 + gitinepector-0.3.2

I suggest a --file-types=all or --file-types regexp that supports "*" or ".*".

Is there any other way to get statistics on files without extensions?
```

Original issue reported on code.google.com by `broad...@gmail.com` on 20 Feb 2015 at 11:39