Show Jekyll’s version before tests

This ensures that the option `--version` works.
I’ve reverted this, but the file doesn’t exist

```
--2014-11-17 06:59:36-- https://github.com/jekyll/jekyll/releases/download/v2.5.1/jekyll-2.5.1.tar.gz

Resolving github.com (github.com)... 192.30.252.128

Connecting to github.com (github.com)|192.30.252.128|:443... connected.

HTTP request sent, awaiting response... 404 Not Found

2014-11-17 06:59:36 ERROR 404: Not Found.
```