Install env-hooks using the catkin_add_env_hooks() macro

This is only a minor update to the newly added env-hooks in `rtt`, `ocl`, `utilrb` and `typelib`.

The env-hooks are now installed using the official `catkin_add_env_hooks()` macro, but only if catkin has been found on the system. I added catkin as a buildtool dependency to the `package.xml` files of these packages, which should not influence non-catkin builds.

For ocl, the `LUA_PATH` will be set to
```
;;/opt/ros/hydro/share/lua/5.1/?.lua
```
instead of
```
;;;/opt/ros/hydro/share/lua/5.1/?.lua
```
which obviously is sufficient:
```
$ export LUA_PATH=";;;/opt/ros/hydro/share/lua/5.1/?.lua"
$ lua -e 'print(package.path)'
;./?.lua;/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua;/usr/local/lib/lua/5.1/?.lua;/usr/local/lib/lua/5.1/?/init.lua;/usr/share/lua/5.1/?.lua;/usr/share/lua/5.1/?/init.lua;;/opt/ros/hydro/share/lua/5.1/?.lua
$ export LUA_PATH=";;/opt/ros/hydro/share/lua/5.1/?.lua"
$ lua -e 'print(package.path)'
;./?.lua;/usr/local/share/lua/5.1/?.lua;/usr/local/share/lua/5.1/?/init.lua;/usr/local/lib/lua/5.1/?.lua;/usr/local/lib/lua/5.1/?/init.lua;/usr/share/lua/5.1/?.lua;/usr/share/lua/5.1/?/init.lua;/opt/ros/hydro/share/lua/5.1/?.lua
```

Here are the direct links to the specific commits in the submodules on GitHub:
* https://github.com/meyerj/rtt/commit/ddf1e7be0cf6c97990e108224ffc40cdeb3d1f90
* https://github.com/meyerj/ocl/commit/12afaba2b5f8f135d66e1f9ffc82b368ad0e52e5
* https://github.com/meyerj/typelib/commit/adb619f086023fb646864628fc4154ac175c02fc
* https://github.com/meyerj/utilrb/commit/eaf652368285c13263ae1c0bc8c79c8ef11492da