Modified RequirementChangeset to better reflect types of changes that can be made to Requirements, and the details associated with that. Added Deserializers for RequirementEvent and RequirementChangeset. Modified Requirement to add Users and Dates for creation of Requirement (not needed for Iteration 1, but no harm putting it in so that the DB sub-team can known it needs to be implemented). Small edits to RequirementStatus and RequirementTest to reflect above changes. Contributor: Tushar N.