The test runs sqlgen load against the cluster and in round robin order makes
nodes stop and continue. After each transition consistency check is done. This
facilitates testing crawling nodes.

Usage with gcomm backend:

./run.sh [N]

Usage with vsbes backend:

GCS_TYPE=vsbes VSBES_ADDRESS=192.168.0.1:5678 ./run.sh [N]

where N is the number of stop/cont transitions. I.e. N=1 means that 1 node will
be killed and restarted. If N is omitted it goes forever.
