Update clone panel to use input group.

Use clone panel in `Git Access` section of wiki.

#### Clone Panels
![clone_panel_wiki](https://f.cloud.github.com/assets/2117996/1865728/63056378-7818-11e3-9c50-033c2626d49e.png)
![clone_panel](https://f.cloud.github.com/assets/2117996/1865729/6307a5b6-7818-11e3-9b44-88a6f0c5c196.png)

The screen shots don't really show much, because the styling hasn't changed. This just uses Bootstraps [input-group](http://getbootstrap.com/components/#input-groups-buttons) rather than trying to recreating it.