Revaluate tests in Brain Observatory test notebook

[wbwakeman]

Recently, we observed tests failing for the brain_observatory test_notebook
99bb33a

The cause turned out to be a misconfiguration of a backup of the test warehouse needed to download NWB files for the tests. A minor archaeological expedition reveals that this backup test warehouse was used because the "main" test warehouse is taken down and rebuilt each night ( http://jira.corp.alleninstitute.org/browse/ABS-74 ).

The current issue was solved by pointing it instead at the production warehouse, which should have the expectation that it is up and working almost all of the time.

We should re-evaluate the purpose of downloading these NWB files from any warehouse. It may be that these tests would be better rewritten to use other testing infrastructure.