* Fix the pool version SQS service to always be mocked before every
test. Before we had to manually set it up before every test dealing
with pool versions.
* Fix it so that we reconnect to the post/pool version databases before
every test. Before using $ARCHIVE_DATABASE_URL to set the database url
failed because environment variables weren't loaded by dotenv yet when
connections were first established.
The Rails convention is for test/helpers to be used for testing the view
helpers in app/helpers. We were using it to store certain utility
methods instead. Move these to test/test_helpers so that test/helpers
can be used for its intended purpose.
