Adding env variables for OKS-GIT

The cm_setup script is modified to add environment variables needed to activate the GIT back-end for OKS. when merged, we need to coordinate for the actual deployment of this.

added CMake label

merged

mentioned in commit 66fbb672

Will submit to nightly tomorrow, so it's there by Tuesday morning.

I think for runtime setup for tbed users, it needs deployment on cvmfs.