scripts/sloccount: Print repository information

This commit transforms:

```
$ ./scripts/sloccount.sh
pip-db 0.3.4 - Source lines of code
Thu Feb 13 21:32:11 GMT 2014

Build system: 969
...
```

into:

```
$ ./scripts/sloccount.sh
Commit: 9b827df2e1b87ca3809ddc687f58a20ff1ad851f
Date:   Thu Feb 13 21:23:49 2014 +0000
Rel:    pip-db 0.3.4

Build system: 969
...
```

Issue #237.
Merge branch 'issue/237'