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.
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