This adds a new tcmu-runner setting "tcmur_cmd_time_out" which is the
number of seconds to wait for a command to complete before logging the
command as stuck and it's completion time.

The new setting can be passed into the dev's config string like

targetcli fil example:

cfgstring=;tcmur_cmd_time_out=5;/dev/sdc"

rbd:

cfgstring=;tcmur_cmd_timeout=5;/rbd/test_image;osd_op_timeout=30

Signed-off-by: Mike Christie <mchristi@redhat.com>