(maint) Handle exceptions in emit_logs / teardown

[Iristyle]

• Previous commit raises ContainerNotFoundError when a call to docker inspect fails, which can cause emit_logs and teardown_cluster to raise exceptions

  These are often called from an after(:suite) or after(:all) which can lead to unexpected failures in spec suites that don't properly cleanup or emit useful information

[Iristyle]

Merging this now to address the cleanup issues that cropped up as part of #160