Avoid deprecation warning from docker.

Original message: 
```
$ sudo docker.io run -d -name gitblit -p 443:443 -p 80:80 -p 9418:9418 -p 29418:29418 jmoger/gitblit
Warning: '-name' is deprecated, it will be replaced by '--name' soon. See usage.
```
Merge pull request #2 from dietmarw/patch-1

Avoid deprecation warning from docker.