This fix repository cloning.

You need to specify the url scheme if you want to pass the SSH server port.
If not you got :

```
Rugged::NetworkError (Early EOF):
  /data/redmine-repositories/jbox/.rvm/gems/ruby-2.0.0-p451/bundler/gems/gitolite-rugged-5dbfc8ad70cb/lib/gitolite/gitolite_admin.rb:286:in `clone_at'
  /data/redmine-repositories/jbox/.rvm/gems/ruby-2.0.0-p451/bundler/gems/gitolite-rugged-5dbfc8ad70cb/lib/gitolite/gitolite_admin.rb:286:in `clone'
  /data/redmine-repositories/jbox/.rvm/gems/ruby-2.0.0-p451/bundler/gems/gitolite-rugged-5dbfc8ad70cb/lib/gitolite/gitolite_admin.rb:89:in `initialize'
```