Refactor v2 cartridge SDK location and accessibility

Move the Bash SDK into a normalized location and add a stub Ruby SDK
file. Add support for two new environment variables:

- OPENSHIFT_CARTRIDGE_SDK_BASH: the absolute path to the Bash SDK file
- OPENSHIFT_CARTRIDGE_SDK_RUBY: the absolute path to the Ruby SDK file

Update all references to the old Bash script to use the new environment
variables.