Setting up to use y3_cluster_cpp through spack and CVMFS

Setup spack, and cosmosis

source /cvmfs/des.opensciencegrid.org/users/cosmosis/neutrinoless_mass_function_2-20200630/setup-env.sh
spack load -r gcc@8.2.0
spack load -r cosmosis@neutrinoless_mass_function_2
spack load -r cmake