wip
Integration test runner support for SIGTERM & SIGKILL

SIGKILL was performing a graceful termination including deleting
containers. This is changed to SIGTERM and SIGKILL is reserved for
shooting garden in the head, although the metaphors are mixed.

Signed-off-by: Steve Powell <spowell@pivotal.io>
Transfer to cf_lager and modify test logging to avoid noise.

Also fix bug in runner.go which threw away signals.
Changed meaning of signals sent to test runner:

SIGQUIT means clean up the containers, the garden process (SIGKILL) and the temporary directories
SIGKILL, SIGTERM and SIGINT are passed through to the garden process

Signed-off-by: Glyn Normington <gnormington@pivotal.io>

Re-order prune

System resources must be freed after the fence is dismantled because
freeing system resources runs destroy.sh which deletes the directory
containing the persistent fence.

Also rework the recovery test. The only case in which a container
is still pingable after recovery is where garden was previously shut
down gracefully.

Also when cleaning up garden in the test runner, shut down garden
gracefully to avoid test flakiness when the temporary directory ends
up in an unusable state.

With these changes, all the tests run (under fly).