Added rtt_rosbuild_tests package

This package does not run automatic tests yet, as it will not be recognized by catkin.

In order to test rtt_ros_integration with rosbuild, run
```
rosmake rtt_rosbuild_tests && rosrun rtt_rosbuild_tests test test_rtt_ros_rosbuild
```
This will start an deployer running a test component that streams `rtt_rosbuild_tests/String` messages on topic `chatter`.