subtests.docker_cli.kill: Add non-tty variant

This modification enables all docker_cli/kill subtests to run on
tty and nontty container. It's not perfect, but it does the job.

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
subtests.docker_cli.kill: Split kill test into multiple ones

Split docker_cli/kill test into docker_cli/{kill,kill_bad,
kill_parallel_stress,kill_stopped,kill_stress} tests.

Additionally change the test_duration from 10s to 60s (for test
development 10s was used, 60s is the least what can be called testing)

Signed-off-by: Lukáš Doktor <ldoktor@redhat.com>
Merge pull request #353 from ldoktor/kill

subtests.docker_cli.kill: Add non-tty variant