Empty fields in liquid template for measures

[jenseeman]

Update the liquid template so that human readable for measures displays "None" when no information is provided in the specification for:

1. Optional measure populations for the given measure scoring type
2. Supplemental Data Guidance
3. Improvement Notation Guidance
4. Supplemental Data
5. Risk Adjustment
6. Stratifications
7. Rate Aggregation
8. Rationale
9. Purpose
10. Guidance (Usage)
11. Clinical Recommendation
12. References
13. Definition