Flaky annotator behavior in test.

[gfr10598]

About one in 5 runs of the manager_test unit test fails for the use-directory branch. Looks like one of the fields has complete garbage in it for at least one run here:
https://travis-ci.org/m-lab/annotation-service/builds/487251888
Please create a new instance rather than restarting this travis test, so we don't lose this test record.

[gfr10598]

Another flake:

--- FAIL: TestE2ELoadMultipleDataset (34.94s)
manager_test.go:191: 0:
Got
{"Geo":null,"ASN":null}
expected
{"Geo":{"continent_code":"AS","country_code":"TH","country_code3":"THA","country_name":"Thailand","region":"40","city":"Bangkok","latitude":13.754,"longitude":100.501},"ASN":null}
manager_test.go:191: 1:
Got
{"Geo":null,"ASN":null}
expected
{"Geo":{"continent_code":"AS","country_code":"TH","country_code3":"THA","country_name":"Thailand","region":"40","city":"Bangkok","latitude":13.754,"longitude":100.501},"ASN":null}
FAIL

[gfr10598]

Here is one that looks like there is still a sorting problem:
manager_test.go:191: 0:
Got
{"Geo":{"continent_code":"NA","country_code":"JM","country_code3":"JAM","country_name":"Jamaica","region":"cz","postal_code":"\ufffd\ufffd#\ufffd7\u001e\ufffd82","latitude":511.258,"longitude":622.468},"ASN":null}
expected
{"Geo":{"continent_code":"AS","country_code":"TH","country_code3":"THA","country_name":"Thailand","region":"40","city":"Bangkok","latitude":13.754,"longitude":100.501},"ASN":null}
manager_test.go:191: 1:
Got
{"Geo":{"continent_code":"NA","country_code":"JM","country_code3":"JAM","country_name":"Jamaica","region":"cz","postal_code":"\ufffd\ufffd#\ufffd7\u001e\ufffd82","latitude":511.258,"longitude":622.468},"ASN":null}
expected
{"Geo":{"continent_code":"AS","country_code":"TH","country_code3":"THA","country_name":"Thailand","region":"40","city":"Bangkok","latitude":13.754,"longitude":100.501},"ASN":null}
FAIL