python: qisys.sh: add PreserveFileMetadata class
python: qisys.sh: add PreserveFileMetadata class

This class, to be used in with-statement, saves and restore times and
permissions on the given file.

Change-Id: Id8ce33559a5b25074377d654fa86262872fea137
Reviewed-on: http://gerrit.aldebaran.lan/60981
Tested-by: gerrit
Reviewed-by: smartin <edaf33f3e53483e687d304aa81a03bb5a17b9ddf@aldebaran-robotics.com>

aldebaran/qibuild,aldebaran/qibuild,aldebaran/qibuild,aldebaran/qibuild