Add employee start and end dates
Select from current employees on Reviews

Either the Reviewee or set of Reviewers should be selected from a list
of current employees
Ignore AA resource definitions from code coverage
Extract common employees query into controller concern

The same employees query needed to be shared between Reviews and
ReviewAssignments. This commit extracts that query into a shared
controller concern and includes it in the respective controllers
Change "Review Stats" to "Reviewee Stats"

For great clarification justice
Color submission status links on Review page

Submission status tags were color-coded on the ReviewAssignment's
listing page. Request came in to color-code the submission status
buttons on the Review page's Reviewers listing similar to the
ReviewAssignment's listing page. This commit achieves that.