Card origin_cartridge_31 - Add support for LD_LIBRARY_PATH_ELEMENT

Currently OpenShift does not manage the `LD_LIBRARY_PATH` for cartridge and they set/unset this environment variable as they want. This cause problems for Jenkins build and introduce situlations where two cartridges fighting for `LD_LIBRARY_PATH`. This PR should add support for managing this environment variable by Node, in similar matter that we manage `PATH` nowadays.

Cartridge writers can use `LD_LIBRARY_PATH_ELEMENT` variable to say what directory they want to append into the global `LD_LIBRARY_PATH`.

- [x] Add support for LD_LIBRARY_PATH_ELEMENT in `node/.../environ.rb`
- [x] Add unit tests for environ.rb
- [x] Update mariadb cartridge
- [x] Update mysql cartridge
- [x] Update postgresql cartridge
- [x] Update python cartridge
- [x] Update ruby cartridge
- [x] Update nodejs cartridge
- [x] Update zend cartridge
- [x] Fix rhcsh so users can see LD_LIBRARY_PATH when they 'ssh' into gear.
- [x] Fix database carts to advertise LD_LIBRARY_PATH when scalable
- [x] Fix oo-trap-user and cron_runjobs.sh script
- [x] Squash the commits ;-)
- [x] Update documention

Trello card -> https://trello.com/c/BB2errnd/31-8-handle-multiple-catridges-having-their-own-ld-library-path