Fix test for change in input
Remove unnecessary test setup step

This waitgroup was replaced with a combiner-based implementation in
a previous commit.
Source tracking

This adds a flag to Jobs that can be used to determine whether they came
from SQS or HTTP.  It's necessary for debugging and to ensure that jobs
aren't wastefully shuffled back and forth between the local queue and
SQS.
Properly handle message deserialization failure

The only thing to do is log it and delete the message, since we don't
want it to fail continuously.
Generate UUID outside of setup

This was removed from setup for some reason, so now has to be done at
deserialization time.
No longer dangerous, CombinerServer doesn't have a queue anymore
Don't print response unless an error occurs
Modify scale alarms to know about SQS

Since we overflow jobs to SQS once local queues reach a given threshold,
we can no longer use local queue size as a metric for when to scale up.
We can use the size of the SQS queue, but SQS reporting is only
refreshed in cloudwatch every 5 minutes.  The most responsive metric is
our custom excess one that tracks the net job count every minute.