Update `prepare' functionality:
    
        - Rename `prepare_doEnvironment.sh' to `prepare_getEnvars.sh' and
          update related files to reflect the change. 
          
          The name changing came because we aren't doing any environment
          here, but getting a list of some of the relevant environment
          variables used by `centos-art.sh' script. So, changed the name
          to prevent any confusion.