rocon_msgs: 0.7.4-0 in 'indigo/distribution.yaml' [bloom]

Increasing version of package(s) in repository `rocon_msgs` to `0.7.4-0`:

- distro file: `indigo/distribution.yaml`
- bloom version: `0.5.2`
- previous version for package: `0.7.3-0`

## concert_msgs

```
* concert client messages with a more expansive set of states.
* conductor graph msg listing concert clients of all states (useful for monitoring).
* Contributors: Daniel Stonier
```

## rocon_app_manager_msgs

```
* GetStatus removed in favour of a newly created Status latched publisher.
* App -> Rapp refactoring.
* Contributors: Daniel Stonier
```

## rocon_device_msgs

- No changes

## rocon_interaction_msgs

```
* a pairing status message, #92 <https://github.com/robotics-in-concert/rocon_msgs/issues/92>
* provide our remocon name when requesting an interaction (now used by pairing), #92 <https://github.com/robotics-in-concert/rocon_msgs/issues/92>
* additional error codes for pairing, #92 <https://github.com/robotics-in-concert/rocon_msgs/issues/92>
* remocon status now correctly listing the set of running apps (not just one)
* Contributors: Daniel Stonier
```