Generate random absence data

Depends: HR-224

The sample data should include:

• 4 AbsencePeriods
• AbsenceEntitlements for each employee for the duration that they're employed with the organization. The duration of employment should cover 1-4 AbsencePeriods
• A variety of absence-requests, including:
• Completed and Scheduled requests
• Sick and Vacation
• High-level request activity ("Sick" activity for Jan 5-8) and low-level detail activity ("Absence" activity Jan 5, Jan 6, Jan 7, and Jan 8)
• Requests encompassing a single day
• Requests encompassing multiple days (with all days used)
• Requests encompassing multiple days (with some days blank)