Add composite controller interface

Composite controller allow use several hardware interfaces in one controller. This commit is not change existing code, only adds new functionality.

Example:

```c++
class MyController: public composite_controller_interface::CompositeController3<
                                       hardware_interface::PositionJointInterface,
                                       hardware_interface::ImuSensorInterface,
                                       hardware_interface::ForceTorqueSensorInterface>

{
public:
  bool init(TypeHW *hw, ros::NodeHandle &n)
  {
    hardware_interface::PositionJointInterface *pos_iface;
    hardware_interface::ImuSensorInterface *imu_iface;
    hardware_interface::ForceTorqueSensorInterface *ft_iface;
    hw->get(&pos_iface, &imu_iface, &ft_iface);

    // Use interfaces

  }
 ...
};

```