Test backend by modifying database

[hardbyte]

The tests are currently written to work entirely through the REST api - this is good for e2e style tests as we don't have to have special access to the deployment other than normal API access.

There are however lots of better tests we could write if we could edit the database, the object store and redis. This issue is to create some of those lower level tests and add them to jenkins.

test that errors get handled when:

• expected CLK/result files are not in object store
• expected rows are missing from database

[hardbyte]

https://datamade.us/blog/transactional-testing