Relase 1.2.0 of cdo.{rb,py} + some additions to upcomming 1.2.1 (refs #3047, refs #3048, refs #3046)

1.2:
* Ruby now uses the same keys like the python interface, i.e. :input and :output
  instead of :in and :out
* :returnArray will accept a variable name, for which the multidimesional
  array is returned

1.2.1:
* new return option: Masked Arrays
  if the new keyword returnMaArray is given, its value is taken as variable
  name and a masked array wrt to its FillValues is returned [python]
  contribution by Alex Loew
* error handling: return stderr in case of non-zero return value + raise exception
  contribution from Estanislao Gonzalez [python]
* autocompletion and built-in documentation through help() for interactive use
  contribution from Estanislao Gonzalez [python]