drop gridFileList.txt output

we don't need it (not very useful; also, now that jobs can be
dynamically allocated it's easier to just check bigpanda.cern.ch) In
this way we also avoid the additional container_gridFileList.txt/.
specify a non-default (shorter) suffix for outds
Merge pull request #3 from gerbaudo/shorten-outds

shorten names
Thank you for your suggestion, @sparticlesteve :
the `--outputs "nt:susyNt.root"` option does the trick.
Merging now.