test: use temp dirs; cleanup after
test: use temp dirs; cleanup after

- Different test relying on the same test data paths
  are causing ongoing intermittent test failures on my
  machine (macOS 10.13.3; go1.10).
- This change puts them in temp directories and cleans up
  afterwards.
- I wonder if this is APFS related? I've seen it a few times
  but it suddenly started failing a lot this morning.
- Should maybe extend this pattern if it causes no issues.

opentable/sous,samsalisbury/sous,samsalisbury/sous,opentable/sous,opentable/sous,samsalisbury/sous,opentable/sous,samsalisbury/sous,samsalisbury/sous,opentable/sous