rosbridge_suite: 0.6.8-0 in 'hydro/distribution.yaml' [bloom]

Increasing version of package(s) in repository `rosbridge_suite` to `0.6.8-0`:

- upstream repository: https://github.com/RobotWebTools/rosbridge_suite
- release repository: https://github.com/RobotWebTools-release/rosbridge_suite-release.git
- distro file: `hydro/distribution.yaml`
- bloom version: `0.5.12`
- previous version for package: `0.6.7-0`

## rosapi

- No changes

## rosbridge_library

```
* add a lock to calls to load_manifest - apparently, it's not thread safe
  fixes #103 and #108
* Contributors: Nils Berg
```

## rosbridge_server

- No changes

## rosbridge_suite

- No changes