Merge rtt_ros_comm and rtt_common_msgs into rtt_ros_integration?

As rtt_actionlib and the test packages in [rtt_ros_integration](https://github.com/orocos-toolchain/rtt_ros_integration/tree/hydro-devel) depend on the typekit packages in the [rtt_ros_comm](https://github.com/orocos-toolchain/rtt_ros_comm/tree/hydro-devel) and [rtt_common_msgs](https://github.com/orocos-toolchain/rtt_common_msgs/tree/hydro-devel), they should be integrated in the rtt_ros_integration repository and always released as a unit with the same version number. With catkin and bloom there is no reason to keep them separated anymore and the existing meta-packages for rtt_common_msgs and rtt_ros_comm will still be available.

Merging was already proposed by @jbohren in https://github.com/jhu-lcsr-forks/rtt_ros_integration/issues/44.

Which directory structure do you prefer for the merged repository?
* Merge them as-is in the root of the repository (all packages at the same level)
* Merge them in the `rtt_common_msgs` and `rtt_ros_comm` subdirectories of the [hydro-devel](https://github.com/orocos-toolchain/rtt_ros_integration/tree/hydro-devel) tree in rtt_ros_integration (Note that there will be two similarly named folders `rtt_roscomm` and `rtt_ros_comm` then.)
* Merge them in the `common_msgs` and `ros_comm` subdirectories
* Additionally move the original rtt_ros_integration packages in a `rtt_ros_integration` folder?
* ...

I am not sure if rtt_geometry should also be merged in. These packages have some additional dependencies that might not be available for source builds. The resulting binary packages can still be installed independently.

Currently the [devel-hydro-rtt_ros_integration](http://jenkins.ros.org/job/devel-hydro-rtt_ros_integration/ARCH_PARAM=amd64,UBUNTU_PARAM=precise,label=devel/) job on Jenkins fails because of the missing dependency rtt_actionlib_msgs.