test(store/watch): add test case for slow event consumers
fix(store/watch): fix the slow consumer bug
Merge pull request #573 from cenkalti/stream-bug

Store: Fix slow consumer bug
Merge pull request #574 from unihorn/6

Fix the bug that TestSimpleMultiNodeTls may error sometimes
fix(tests/functional): some squashing mistakes in PR merge

accidental squash mistake in the last PR that was merged caused a
function to be renamed but not it's caller.
chore: rename 'heartbeat timeout' to 'heartbeat interval'

Heartbeat timeout means the period length that indicates heartbeat is
out of service, which is different from heartbeat interval.

So we should use '-peer-heartbeat-interval' instead of
'-peer-heartbeat-timeout' in etcd.