Also, worker tests implemented for redis

Otherwise, concurrent calls to 'IF NOT EXISTS' when creating extension
could result in unique constraint errors.

Also, implement TSRepeatNElseArchive handler in worker

Also, fixes to getting conn info from env vars (for tests)

This doesn't compile yet

simple-worker/Main compiles now but doesn't yet work correctly

Doesn't compile yet

Unit and integration tests work

It should keep looping

Now, there is a WorkerMessage data type which implements metadata
about a job.