This test is designed to verify that an ONOS cluster behaves correctly when some
ONOS nodes are stopped. Currently, we will stop nodes so that each raft partition will
lose a member, but we make sure that there is always a majority of nodes
available in each partition.

As written, the test only supports an ONOS cluster of 3,5, or 7 nodes.
This is because the test doesn't apply to a single node cluster, ONOS clusters
should be deployed in odd numbers, and the partition generation and node
killing scheme used doesn't give the same properties for clusters of more
than 7 nodes. Namely, each partition won't have exactly one node killed.

The gerneral structure for the test:
- Startup
- Assign switches
- Verify ONOS state and functionality
    - Device mastership
    - Intents
    - Leadership election
    - Distributed Primitives
- Stop some ONOS nodes
- Verify ONOS state and functionality
- Restart nodes
- Verify ONOS state and functionality
- Dataplane failures
    - link down and up
    - switch down and up