Make window optional for a job

[sbchaos]

Description
Currently not everyone uses window for size of data to use for job, this should be made optional. People should omit window definition when they need to use all the data in table, or they can use partition to refer to the data.

Acceptance Criteria

• Job spec should not contain window definition when it is not required in the job

Out of Scope

1. Simplification of the definition of window