catkin: 0.6.6-0 in 'indigo/distribution.yaml' [bloom]

Increasing version of package(s) in repository `catkin` to `0.6.6-0`:

- distro file: `indigo/distribution.yaml`
- bloom version: `0.5.9`
- previous version for package: `0.6.5-0`

## catkin

```
* fix rollback of environment when workspace has been deleted (#641 <https://github.com/ros/catkin/issues/641>)
* fix argument handling when cm / cmi is invoked in a symlinked folder (#638 <https://github.com/ros/catkin/issues/638>)
```