Two more PEP8 fixes

cmdlib: Avoid wrapping using backslash

gnt_group: Avoid ** magic using keyword arguments (the “pep8” tool
doesn't like the inline comment in this case and will complain about
spaces around the “**” operator)

Signed-off-by: Michael Hanselmann <hansmi@google.com>
Reviewed-by: Iustin Pop <iustin@google.com>