Catkin env-hooks in orocos_toolchain

- Renamed the env-hook from `orocos.bash` to `orocos_toolchain.sh` because of the similarity to the env-hook `10.orocos.sh` in the new [rtt_ros](https://github.com/jhu-lcsr-forks/rtt_ros_integration/tree/hydro-devel/rtt_ros/env-hooks) package (which probably also should be renamed to `10.rtt_ros.sh`).
- Enabled the env-hook for all kind of shells (not only for bash).
- Prefix and clean up temporary variables to not pollute the environment.
- Make ruby optional (for the case the env-hook is used for rtt and ocl only).
- Commented setting of `(DY)LD_LIBRARY_PATH`, as it does not seem to be required. At least there are no libraries that are installed to `@CMAKE_INSTALL_PREFIX@/lib/orocos` without a specific target suffix. However, I am not sure if typelib requires the `LD_LIBRARY_PATH` to be set. There isn't anything related to `LD_LIBRARY_PATH` in the  [env.sh](https://github.com/orocos-toolchain/orocos_toolchain/blob/master/env.sh) script.

Additionally to this minor update I would propose to remove the env-hook from the orocos_toolchain meta-package and add individual env-hooks in rtt, typelib and utilrb instead as required.

Also orocos_toolchain should probably not depend on catkin during build-time as this might affect AutoProj-based builds without having catkin installed. An env-hook can be easily installed without involving catkin with cmake's `configure_file()` command and installation to `etc/catkin/profile.d`. In this case, installing only the toolchain would not install catkin's `setup.*` files, but the env-hook would still be used if orocos_toolchain is installed to `/opt/ros/DISTRO/` or some other catkin install-space. `catkin_make_isolated` installs light-weight setup scripts for pure cmake projects, but they do not check if there are env-hooks in etc/catkin/profile.d. Not sure 

Can the `env.sh`, `env.mk` and other files be removed from the source folder (in general or only in the catkin branch)? At least `env.sh` probably shouldn't duplicate the env-hooks but include them or vice versa.