Intermittent test failure "verify aggregation respects email preference"

```
  1) Activity Email verify aggregation respects email preference:
     Uncaught AssertionError: 0 == 3
      at /home/travis/build/oaeproject/Hilary/node_modules/oae-activity/tests/test-email.js:339:84
      at /home/travis/build/oaeproject/Hilary/node_modules/oae-email/lib/test/util.js:102:28
      at allDone (/home/travis/build/oaeproject/Hilary/node_modules/oae-activity/lib/internal/email.js:9:9018)
      at /home/travis/build/oaeproject/Hilary/node_modules/oae-activity/lib/internal/buckets.js:9:3854
      at _collectBuckets (/home/travis/build/oaeproject/Hilary/node_modules/oae-activity/lib/internal/buckets.js:9:4310)
      at /home/travis/build/oaeproject/Hilary/node_modules/oae-activity/lib/internal/buckets.js:9:5051
      at /home/travis/build/oaeproject/Hilary/node_modules/oae-activity/lib/internal/buckets.js:9:8270
      at /home/travis/build/oaeproject/Hilary/node_modules/oae-util/lib/locking.js:9:3967
      at b (domain.js:183:18)
      at try_callback (/home/travis/build/oaeproject/Hilary/node_modules/redis/index.js:573:9)
```

`Uploaded "tests.log.gz" to Amazon S3: "oae-testing/travisci/logs/hilary/build-1553-29d5efe06d9f038721739197a1335e7a275c276c-Mon Jun 23 2014 17:31:26 GMT+0000 (UTC).log.gz"`