Merge pull request #235 in CASA/casa6 from CAS-13131 to master
* commit '180d7a53438e00fe2aa50d1d72bfdd952d8ebd13':
prevent attempts to run casatasks (CAS-13131)
casatasks & casatools should suppress ~/.casa/config.py output (CAS-13131)
direct stdout/err to /dev/null when evaluating ~/.config.py and "python -m casatools ..." is used (CAS-13131)