Docker: Pylint cleanup: unused imports

*  Disabled a few messages that can safely be ignored

Signed-off-by: Chris Evich <cevich@redhat.com>
subtests..run_simple: run_signal wait for start

It was sending signal to container before container
had started running.  Probably not a bug since docker
cannot detect when process is ready to receive signals
or not.

Signed-off-by: Chris Evich <cevich@redhat.com>