handle lgc.adbh api changes within regards of backup/restore: * new backup_commands method instead of backup_command * some backend still return command as string as expected by os.system, not subprocess.call

"""pre 3.6 bw compat"""
# pylint: disable-msg=W0614,W0401
from warnings import warn
warn('moved to cubicweb.mail', DeprecationWarning, stacklevel=2)
from cubicweb.mail import *