[JobQueue] Check if the job defines a requestId before using it.

Authored by Pchelolo on Sep 13 2017, 8:13 PM.

Description

[JobQueue] Check if the job defines a requestId before using it.

The Job class unconditionally sets a requestId, but some of the
jobs don't use it and inherit the JobSpecification and don't set
the requestId - in that case obtain it manually.

Change-Id: Iaebac6c921bac3a117acc6f3d26f4202341fad2a