Write an integration test that involves a partition

[enolan]

We want to check that:

A) After a partition, all nodes agree on a winning fork B) Transactions that were in the losing fork get brought over to the winning fork, except for transactions that are invalid on the winning fork C) The transaction pool contains only valid transactions afterward D) The right thing happens to the snark pool? I don't know a lot about it

[wu-s-john]

Seems related #2606