python $OPENSHIFT_PYTHON_REQUIREMENTS_PATH ENV VAR

Example of usage:
rhc env-set OPENSHIFT_PYTHON_REQUIREMENTS_PATH=prod-requirements.txt --app <app>

origin_cartridge_card_54 - https://trello.com/c/uUwu8EWL
Merge pull request #4805 from VojtechVitek/python_requirements.txt

Merged by openshift-bot