Integrate "business transaction" ids in job-instrumented about bootique-job

[andrus]

BTW, there's another thing, which may be outside the scope of the initial implementation but is never the less important - providing TX ids to parallel jobs (e.g. all independent jobs in a "job group" are run in parallel on a thread pool). We may need to think of a solution for this for the future. E.g. storing the TX ID somewhere in the job execution context and passing it down to each child job.

[elena-bondareva]

Note: recording of what has been discussed offline is here PR#53.