Allow direct communication to Openshift through all RBAC-related endpoints

[QuanMPhm]

Dependant on #177, as the next step to merge CCI-MOC/openshift-acct-mgt, we want all functions in the OpenShiftResourceAllocator class that make use of the rbac.openshift.io API to have direct communication with the Openshift cluster. This includes the following functions:

• assign_role_on_user
• remove_role_from_user
• _get_role