FIX set default job ttl as rq's registry ttl

[jaumef]

• FIX set default job ttl as rq's registry ttl

From rq's registry add: https://github.com/rq/rq/blob/master/rq/registry.py#L53

Case to fix

>ttl=None
>ttl if ttl < 0 else 123456 + ttl
None

Other Cases

>ttl=0
>ttl if ttl < 0 else 123456 + ttl
0
>ttl=-1
>ttl if ttl < 0 else 123456 + ttl
-1
>ttl=1
>ttl if ttl < 0 else 123456 + ttl
123457

[coveralls]

Coverage remained the same at 0.0% when pulling bdbcedf on fix_job_ttl into fdb2857 on master.