Update leaders last-leader-msg-time on claim

If a claim was successful, the cohort will have updated their
last-leader-msg-time. This updates the leaders as well.
Keep trying to claim in stress tests

Don't give up trying to claim new work if claim returns nil. Only give up once
a deadline has passed.
Retry claim in election-handoff-test
Add elect prefix to election messages
Retry claims in node test
Sleep a little between retries
Increase deadlines and sleep time
Fix a couple more times
Merge pull request #94 from eric/add-elect-prefix-to-vnode-logs

Add elect prefix to election messages
Merge pull request #92 from eric/keep-trying-to-claim-in-stress-test

Keep trying to claim in tests
Merge branch 'master' into update-leaders-last-leader-msg-time-on-claim

Conflicts:
	src/skuld/vnode.clj
Merge pull request #89 from eric/update-leaders-last-leader-msg-time-on-claim

Update leaders last-leader-msg-time on claim
Merge remote-tracking branch 'factual/master' into fix-improper-format-strings