Output policy data to METSRIGHTS only if a policy is effect (by date)

Test cases
1. No date present
2. Start date and end date present
3. Start date only present
4. End date only present
Included date values and effective flag on Context element
Merge pull request #309 from terrywbrady/master

DS-1697: Output policy data to METSRIGHTS only if a policy is effect (by date)