Corb with pre-defined execution plan

[bbandlamudi]

This is probably going to be the base implementation and an extension which can be item '3' of the enhancement/issue #73.

The execution plan is going to be useful for long running jobs in production when it is required to consider outages or other smaller jobs that may run in between. Also, this will support peak/off-peak load times.

For example:

1. Start with full 4 threads at 2pm
2. At 6pm increase to 16 threads as the it is start of semi off-peak time
3. At 7pm decrease to 8 threads as another small by high load job is going to run.
4. Pause from 10pm to 12pm for deployment window.
5. Resume the job at 12pm and increase thread count to 32 as this is off-peak time.
6. If the job is not complete by 6am - stop it - Is restartable ref: Corb2 needs be restartable #65