Redis sorts zsets lexographically for members with the same priority.
This causes jobs to run out of order. If you submit 11 jobs at the same
priority level, they will run as 1,10,11,2,3,4,5,6,7,8,9.

This adds a zid to the job that prepends the number of digits in the job
id (001)1. This new zset value will be sorted correctly by redis. This
is not desirable as a general purpose id, so it is hidden and the
standard jobid can be used for all external purposes.

The prepended value is stripped off when doing zpop.

Fixing range by and delay code so all tests pass again.

The suggestion to remove 2 characters from the zid seemed reasonable.
Also renaming parseID to stripFIFO to be consistent with the other file.

I didn't like defining the strip FIFO and create FIFO in separate files.
This collocates them in one place next to the getKey call that is used
everywhere.

I was using tab characters, switching to spaces.

Expecting a string was causing a crash when undefined was passed in.
Undefined doesn't resolve to an id, so we return null.