s/Put/Create
s/Put/Create in api_test
Fix scheduler Schedule behavior

Put used to Create+Start, but now it just Creates, so we need to allow
for ErrAlreadyExists in the Schedule behavior.
Scheduler agentrepr.Client interface update
Replace time.Sleep with runtime.Gosched in tests (unrelated)
Update harpoonctl Put -> Create
xf_test not tightly-scoped enough for Gosched
More attempts to fix test on travis (works fine locally)
Try to compensate for bad CPU schedulers in Travis
Merge pull request #151 from soundcloud/fix-agent-client-verbs

Fix agent client verbs