ros_control: 0.7.3-0 in 'hydro/distribution.yaml' [bloom]

Increasing version of package(s) in repository `ros_control` to `0.7.3-0`:

- upstream repository: https://github.com/ros-controls/ros_control.git
- release repository: https://github.com/ros-gbp/ros_control-release.git
- distro file: `hydro/distribution.yaml`
- bloom version: `0.5.12`
- previous version for package: `0.7.2-1`

## controller_interface

- No changes

## controller_manager

```
* Spawner: adding shutdown timeout to prevent deadlocks
* Create README.md
* Contributors: Adolfo Rodriguez Tsouroukdissian, Jonathan Bohren
```

## controller_manager_msgs

- No changes

## controller_manager_tests

```
* make rostest in CMakeLists optional
* controller_manager_tests: fix library linking
* Contributors: Lukas Bulwahn, Paul Mathieu
```

## hardware_interface

- No changes

## joint_limits_interface

```
* make rostest in CMakeLists optional.
* Add hardware_interface to CATKIN_DEPENDS.
* Fix generation of rostests in catkin.
* Contributors: Adolfo Rodriguez Tsouroukdissian, Lukas Bulwahn
```

## ros_control

- No changes

## rqt_controller_manager

- No changes

## transmission_interface

- No changes